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Recipe: Fastest French Onion Soup in a Mug + Cheesy Gruyère Croutons

Recipe: Fastest French Onion Soup in a Mug + Cheesy Gruyère Croutons

Fastest French Onion Soup in a Mug + Cheesy Gruyère Croutons

by Erin Fletter
Photo by Natasha McCone and Kate Bezak
prep time
10 minutes
cook time
4 minutes
1-1 servings

Fun Food Story

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Fastest French Onion Soup in a Mug + Cheesy Gruyère Croutons

It’s high time for a cozy soup recipe that can be whipped up in a flash, don’t you think? French onion soup typically takes hours to produce that deeply caramelized onion-y flavor we love so much. We can get pretty sweet results in the microwave without standing at the stove stirring onions for hours. In this version, the onions soften in butter with a touch of salt and are slightly soured by a touch of vinegar. With this recipe, we’re keeping young chefs focused on the five tastes: sweet, sour, bitter, salty, and umami, and then on building and balancing flavors from there. Onions are so good for our immunity—and so is the grapefruit in our Citron Presse French Grapefruit-Ade! This is the perfect fall or winter recipe to keep the heart and body happy. Enjoy it!

Happy & Healthy Cooking,

Chef Erin, Food-Geek-in-Chief

Fun-Da-Mentals Kitchen Skills

  • chop :

    to cut something into small, rough pieces using a blade.

  • grate :

    to reduce food, like a carrot, to very small shreds or pieces of the same size by rubbing it on a tool with an outside surface that has holes with cutting edges (a grater).

  • knife skills :

    Bear Claw (growl), Pinch, Plank, and Bridge (look out for trolls)

  • microwave :

    to heat or cook food or liquid quickly in a microwave oven, which uses high-frequency electromagnetic waves to generate heat in the food's water molecules.

  • toast :

    to brown and crisp food in a heated skillet or oven, or in a toaster.

Equipment Checklist

  • Toaster
  • Box grater (or hand grater)
  • Measuring spoons
  • Cutting board + kid-safe knife
  • Microwave
  • Microwave-safe mug + cover, like a paper towel
  • Potholders
  • Liquid measuring cup
  • Metal spoon


Fastest French Onion Soup in a Mug + Cheesy Gruyère Croutons

  • 1 T butter **(for DAIRY ALLERGY sub olive oil)**
  • 1 small or 1/2 large yellow onion
  • 1/4 tsp salt
  • 1 C veggie broth
  • 1 tsp apple cider vinegar
  • 1 pinch black pepper
  • 1 pinch sugar (optional)
  • 1 slice French, Italian, or whole wheat bread **(for GLUTEN ALLERGY sub gluten-free/nut-free bread)**
  • 1 oz/slice Gruyère, Swiss, or provolone cheese **(for DAIRY ALLERGY sub Daiya brand dairy-free cheese shreds)**

Food Allergen Substitutions

Fastest French Onion Soup in a Mug + Cheesy Gruyère Croutons

  • Dairy: Substitute olive oil for butter and Daiya brand dairy-free cheese shreds for cheese in Soup. 
  • Gluten/Wheat: Substitute gluten-free/nut-free bread for the Croutons.


Fastest French Onion Soup in a Mug + Cheesy Gruyère Croutons

toast + grate

Toast 1 slice of bread, then break up the toast into bite-sized croutons with your hands. Set them aside. Carefully, grate 1 ounce of Gruyère cheese to equal a handful, or about 3 tablespoons.

chop + tip

Adults may want to cut 1 onion into smaller wedges for younger chefs, then kid chefs can chop the wedges into bite-sized pieces. (Tip: Chill the onion in the freezer before chopping, or have kid chefs hold a piece of bread in their mouths while chopping the onion. This may help prevent their eyes from tearing up!)

measure + stir + microwave

Measure and add 1 tablespoon butter, 1/4 teaspoon salt, and the chopped onions to a microwavable mug. The onions should fill the mug about halfway. Cover the mug and microwave for 2 minutes. Remove the mug with a potholder. Careful! It’ll be hot! Then add 1 cup broth, 1 teaspoon apple cider vinegar, and 1 pinch of black pepper to the mug and stir. Taste: does it need a bit of sweetness to balance flavors? Add 1 pinch of sugar if it does. Cover again and microwave for another minute.

add + microwave

Remove the mug with a potholder. Tuck the croutons into the soup with a metal spoon and top the croutons with shredded cheese. Microwave for a final 30 to 45 seconds to melt the cheese. Let the mug cool slightly and dig in!

Surprise Ingredient: Onions!

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Photo by BearFotos/

Hi! I'm Onion!

"Did you know that onions are vegetables? My close relatives are chive, garlic, and leek, and I'm a distant cousin of the amaryllis and daffodil. I'm actually the edible bulb of the onion plant!  

History & Etymology

  • The onion is thought to be native to Asia, but there are also ancient remnants from Iran, India, and Egypt.
  • The Egyptians even worshiped onions! They believed their circular shape and layers symbolized eternal life, and often onions were placed in ancient tombs to bring prosperity to mummies in the afterlife.
  • Ancient Greek and Roman athletes used to eat onions to get strong, and they even rubbed onions on their bodies before competing in events like the Olympics.
  • In medieval times, people used onions as a form of currency! Imagine paying bills with a bag of onions!
  • Native Americans in Eastern Canada and the Eastern United States ate a species of wild onion, also called ramps or wild leek. 
  • China is the largest producer of onions. In the US, California grows the most onions.
  • Some people around the world say, possibly as early as 3,000 years ago in China, that onions can predict the weather. 
  • There is even a saying about onions and the weather that goes like this: "Onion's skin very thin, mild winter coming in; onion's skin thick and tough, coming winter cold and rough."
  • The word "onion" comes from Middle English from the Old French "oignon," based on the Latin "unionem," literally "union," indicating the unity of the layers of the onion. 


  • Onions are part of the "Allium cepa" genus. "Cepa" is Latin for "onion." The common onion plant grows from 6 to 18 inches tall. 
  • They have hollow green leaves that grow upward and fan out of a covered stem from the top of the bulb. Roots extend out of the basal plate at the bottom of the bulb into the soil.
  • The onion bulb is described as having a "globe" shape. It is made up of fleshy leaves that grow around the flower bud in the middle. These fleshy leaves are covered by scaly leaves, the onion's "skin," that dry out and become papery when it is time for the onion to be harvested.

How to Pick, Buy, & Eat

  • There are lots of onion varieties! Green onions (also called scallions or spring onions) are mild in flavor, and both the bulbs and top leaves can be eaten. They are often found in salads and stir-fry dishes. They have a small, not fully developed white bulb end with long green stalks. The white shaft of the plant extends from the roots to the leaves.  
  • Yellow onions can be pungent or sweet. The Spanish onion is a common pungent variety typically found in grocery stores. The Vidalia is a sweet onion from the state of Georgia, and the Walla Walla is a sweet onion from the state of Washington. 
  • White onions have a sharp flavor and are often used in Mexican cooking. Red onions are sweeter than yellow and white onions and are used raw in salads and on burgers. 
  • The shallot is a smaller variety with a milder pungent flavor often used in sautéed dishes, sauces, and stocks. Pearl onions are tiny bulbs that are mild in flavor and great for pickling.
  • Store whole raw onions in a cool, dark location. Cut onions will keep in the refrigerator for about a week. Store them in an airtight container that will not absorb their smell (i.e., glass rather than plastic).
  • Onions can cause eye irritation and tears when you cut into them. This is because a chemical compound called syn-propanethial-S-oxide is released into the air when you slice an onion, and tears are produced to wash it away. 
  • Chilling onions in the refrigerator or a bowl of ice water before cutting them can decrease the amount of irritation. Other suggestions include using a sharp knife, holding a piece of bread in your mouth while you slice, or wearing goggles. 


  • Onions have a high water content, about 89 percent, and are low in calories. They contain low amounts of protein, fiber, and essential nutrients.

History of French Onion Soup!

Photo by photosimysia/
  • Onion soup actually originated in ancient Rome. There are a few different origin stories for this classic dish, but onion soup has been around for 8,000 years, so it stands to reason that many cultures would claim this tasty soup!
  • It wasn't until the 1700s that the French perfected onion soup and made it what it is today. One story of its beginning is that French chef Nicolas Appert, who invented canning to preserve food, prepared the soup for the Duke of Lorraine one night at a hotel, and the duke loved it so much that he took the recipe to the French royal court of Louis XV. 
  • The word "soup" came from the old French word "soupe," which referred to a broth that people soaked up with bread, not a spoon. 
  • French onion soup is usually based on a meat stock and onions served in individual, oven-proof bowls or ramekins, covered with croutons or a bread slice, sprinkled with cheese, like Gruyère, and then broiled or baked until the cheese melts.

Let's Learn About France!

Photo by Alliance Images/
  • Bonjour (hello)! Bienvenue en (welcome to) France and the spectacular Eiffel Tower in Paris, the Mona Lisa, painted by Leonardo da Vinci, and ancient Roman ruins in the Provence region.
  • France is a European country, and its official name is the French Republic. The capital city is Paris, which also has the most people. 
  • France's land area is 248,573 square miles. That is almost the size of the US state of Texas! The number of people in France is 67,874,000, about 43 percent more than in Texas.
  • The official and national language is French, which is also the official language in 12 other countries, and a co-official language in 16 countries, including Canada. 
  • France's government consists of a president, a prime minister, and a parliament and is divided into regions and departments rather than states and counties.
  • The French have a well-known motto, "Liberty, Equality, Fraternity."
  • In addition to the Eiffel Tower, France is known for the Louvre, the most visited art museum worldwide (the Mona Lisa resides there), the Notre-Dame Cathedral, and the French Riviera (Côte d'Azur) in southeastern France on the Mediterranean coast.
  • France is famous for the "beaux-arts" (fine arts). Paris is still home to many artists and great painters, artisans, and sculptors. Great literature came from French authors, such as Victor Hugo's novels Les Misérables and The Hunchback of Notre Dame.
  • Paris has two popular nicknames. The most common is "The City of Light" (La Ville Lumière), which came about because Paris was the first European city to implement street lighting in 1860, lighting up the city with 56,000 gas street lamps. The second is "The City of Love," (La Ville de L'amour). This name is probably due to Paris being considered one of the most romantic cities in the world and the high number of marriage proposals at the Eiffel Tower!
  • French cuisine is known for its freshness and high quality. Many of the world's greatest pastries originated in France, such as the croissant, eclair, and macaron!
  • Other French foods are escargot (snails!), baguette (bread), ratatouille (roasted tomato, zucchini, and eggplant—remember the movie?!), and crepes (very thin pancakes).

What's It Like to Be a Kid in France?

  • Most kids start school (preschool) at around age three. Depending on the area and the school, students go to school 4 to 5 days a week. They often get a 1½-hour lunch break, and some kids go home for lunch. 
  • Dinner is served at 7:30 pm or later, so afternoon snacks are essential. "Le goûter" (goo-tay), or afternoon tea, often includes a "tartine," a slice of bread topped with something sweet or savory (like cheese, butter and jam, or Nutella). Other popular snacks are yogurt, fromage blanc (white cheese), and fruit. 
  • Popular sports for kids are soccer, bicycling, and tennis.
  • There are several parks in France, in and around Paris. Napoleon III even designed one of them, the Bois de Boulogne, where you can find beautiful gardens, lakes, a zoo, an amusement park, and two horse racing tracks. In addition, kids can go on pony rides, play mini-golf, and race remote control boats at many public parks.  
  • Of course, kids can also go to the most popular theme park in Europe, Disneyland Paris, which opened in 1992. While there, kids can go on a ride unique to Disneyland Paris: Ratatouille: The Adventure!

THYME for a Laugh

Why doesn't bread like warm weather? 

Things get toasty!

THYME for a Laugh

What did the butter say to the bread? 

"I'm on a roll!'

The Yolk's On You

What did the boy do when he saw an onion ring?

He answered it!

The Yolk's On You

I’m allergic to green onions.

Every time I eat them, I break out in chives!

THYME for a Laugh

When does bread rise?

When you yeast expect it to!

That's Berry Funny

What do you call a hobbit with a healthy appetite?

Lord of the Onion Rings!

Lettuce Joke Around

What do you call an onion that won’t hold water?

A leek!

The Yolk's On You

Why did Mr. Potato Head have a cell phone?

In case Mr. Onion Rings!

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