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How to Caramelize Onions and Make French Onion Soup

A bowl of hot french onion soup garnished with fresh thyme with two pieces of bread next to the bowl.
Emilee Unterkoefler

Caramelizing onions is easier than you think. Learn how to transform those sharp little slices into a sweet ingredient perfect for French onion soup and many other recipes.

We’ll give you the rundown on caramelized onions and provide steps to show you how to make them. From there, you’ll learn how to make French onion soup, a rich a flavorful entree or starter your guests will love.

What Are Caramelized Onions?

Onions naturally give off a sharp flair when eaten raw, but those little astringent slices turn into something quite special when simmered over low heat.

When onions are cooked over a long period of time, they begin to break down and soften up, giving them a quality that differs greatly from their original form. We call this process “caramelization.”

During the cooking process, the sugar in the onion begins to break down, which results in a deep brown colored onion. Caramelizing onions takes time and patience, but if done accurately, the rich and nutty flavor accompanied by a lovely touch of sweetness creates heavenly results.

Time is on your side when caramelizing onions, so once your onions start to brown, you are about halfway there. Keep in mind the process takes up to 45 minutes, and for genuinely flavored onions, we don’t recommend rushing.

Deglazing the pan is an essential step in the process that ensures you are picking up all the delicious brown bits, and you’ll likely deglaze a few times before your onions are finished.

So these caramelized onions seem cool and all, but can we use them in other recipes besides French onion soup?

How Do I Use Caramelized Onions in Cooking?

Caramelized onions do an excellent job of sprucing meals up and turning them from boring to downright fancy and flavorful.

  • Top pizza: On your next pizza night, skip the classic pepperoni and cheese and top your pizza with a bit of roasted broccoli, tomatoes, garlic, and a generous sprinkle of caramelized onion. Don’t forget the fresh mozzarella, goat cheese, and when it’s bubbly hot and out of the oven, finish it with arugula and balsamic glaze.
  • Mix into a casserole: You don’t need much imagination here; caramelized onions will taste amazing in most casseroles filled with hearty vegetables and meats.
  • Smother a steak: Nothing says flavor like smothering a medium-rare ribeye topped with a rich slice of compound butter and a generous spoon (or two) of caramelized onions.
  • Make a dip: Cream cheese and sour cream are best buds when paired with caramelized onions and a bit of salt, pepper, and spices; it’s the ultimate French onion dip for potato chips.
  • Top a burger: Imagine a greasy burger layered with barbecue sauce, sharp cheddar, crispy slices of bacon, and of course, caramelized onions seeping out from each bite. Yum!
  • Make some soup: Most of us know about caramelized onions for their notorious counterpart, French onion soup, and we’ll show you the steps for making it below. But aside from that fancy broiled treat, feel free to add those sweet onions to any soup that needs a little oomph in the flavor category.

We’ve only provided a few delicious ways to use this ingredient, but from hot-pressed paninis to fancy flatbreads, there is so much more you can do with caramelized onions.

A Few Tools You’ll Need

Caramelizing onions is pretty easy, but having the right tools makes the process that much more convenient. A heavy-bottomed pan is your best bet when cooking the onions, and for that traditional appeal, you’ll love having oven-friendly crocks on hand too.

Le Creuset Enameled Dutch Oven

A white Le Creuset 5.5 quart Dutch oven presented with a bunch of asparagus next to it.
Le Creuset

The iconic Le Creuset Dutch oven is one of those pieces of cookware that I couldn’t live without. The heavy bottom and durable construction make it reliable, and the enameled non-stick properties appeal to cooks of all levels.

The kitchen workhorse does a fine job of cooking your meal (on the stove or in the oven) and makes a stunning centerpiece on your dinner table.

It’s just what I use to caramelize onions, but I also love making soups, stews, braises, casseroles, and more with this beautiful piece of cookware.

Le Creuset 5.5 Qt Dutch Oven

This classic Dutch oven will last for generations.

Traditional Crocks

Two images displaying the Tauci French onion crocks.
Tauci

Traditionally, you’ll serve a hot French onion soup in individual crocks like these. These oven-friendly soup bowls will hold up to 15 oz of whatever you have cooking, and they are great for chili and stews too!

Tauci French Onion Crocks

Want to make individual portions the most traditional way? Try these.

How to Caramelize Onions and Make French Onion Soup

You almost know everything there is to know about caramelizing onions, but making them at home is your guaranteed path to success. After you make caramelized onions, check out the recipe for making a classic French onion soup, too.

Ingredients:

  • 3-4 medium-large onions
  • Olive oil, to coat the bottom of your pan
  • Splash of white wine (red wine, stock, or water will do)
  • Pinch or two of salt

Instructions:

  1. Slice the stem end of your onion, but leave the root end on. Cut your onion in half, then peel the skin off of both halves.
Slicing an onion in half using a long chef's knife.
Emilee Unterkoefler

2. Make multiple uniform slices, getting as close as possible to the root without cutting through the root. The root will keep your onion intact and keep it from bleeding, which will keep your tears from flowing.

Slicing an onion vertically multiple times, with onions and onion peels on the side.
Emilee Unterkoefler

3. Slice the root off, and use both hands to pull the slices apart, and place them in a bowl. Continue working through all of the onions.

A small pile of uniformly sliced onions with a few halved onions and some peels on the side of the cutting board
Emilee Unterkoefler

4. Coat the bottom of your Le Creuset or any heavy-bottomed pan with oil, turn your heat to medium, and add the onions and a pinch (or two) of salt.

Three large onions sliced and placed into a 5.5 quart Le Creuset Dutch oven.
Emilee Unterkoefler

5. Cook your onions on medium-high heat for about five to ten minutes until you notice your onions begin to soften, and brown bits begin to form at the bottom of your pan.

Onions in a Le Creuset Dutch Oven starting to brown, with a wooden spoon inside.
Emilee Unterkoefler

6. Pour a splash of cold liquid (we use white wine) and use a wooden spoon to scrape along the bottom of your pan to pull up the brown bits. If you don’t have wine on hand, feel free to use stock or water to deglaze. You might have to deglaze a few times during the cooking process. Turn your heat to med-low.

Onions beginning to deepen in color as they cook over medium heat.
Emilee Unterkoefler

7. Stir infrequently, but enough to ensure your onions don’t burn. It will take about 45 minutes to produce caramelized onions.

Onions starting to reach the caramelization stage.
Emilee Unterkoefler

Those onions look so yummy, and they are almost fully caramelized! What do you plan to use your caramelized onions for? If you aren’t sure yet, we recommend going with the classic; French onion soup!

French Onion Soup Recipe

French onion soup is a classic recipe that boasts a beefy broth filled with lusciously soft caramelized onions and a crusty cheese topping. It’s a timeless soup you’ll find on many restaurant menus, but nothing compares to making it from scratch at home.

Because you already know how to make caramelized onions, you are already halfway there. Here’s how to use them to make a traditional French onion soup.

Ingredients:

  • Caramelized onions from 3-4 onions
  • 1 large garlic clove, minced
  • 6- cups of beef stock
  • 1 tablespoon of fresh thyme leaves
  • 2-3 tablespoons of olive oil
  • 12-14 slices of French baguette
  • 8 slices of gruyere cheese
  • 3 tablespoons of panko breadcrumbs
  • 3 tablespoons of grated parmesan
  • 1 teaspoon of parsley, finely chopped
  • 1/4 teaspoon of garlic powder

Instructions:

  1. Preheat your oven to 400 degrees Fahrenheit. Drizzle olive oil over your baguette slices, then place the bread pieces on a sheet pan and toast for about 5 minutes or until they begin to turn a golden brown. After removing the sheet pan, turn your oven from bake to broil and set it to 350 degrees Fahrenheit.
Multiple slices of French baguette placed on a sheet pan, freshly toasted in the oven.
Emilee Unterkoefler

2. Place caramelized onions and minced garlic into an enameled Dutch oven, then add stock and fresh thyme. Bring the soup to a simmer and cook for at least 25-30 minutes—season to taste with salt and pepper.

Stock, fresh thyme, and garlic added to the Le Creuset Dutch oven.
Emilee Unterkoefler

3. In a small bowl, while your soup simmers, combine the panko bread crumbs, parmesan cheese, parsley, and garlic powder, and set the bowl aside. Ladle soup into the crock, filling each about 3/4 full, then place two or three toasted baguette slices on top.

Two crocks filled with french onions broth, topped with three slices of toasted french baguette crostinis.
Emilee Unterkoefler

4. Layer two slices of Swiss cheese, then about a tablespoon of panko parmesan topping over the gruyere cheese. The panko topping is an adaptation of a recipe inspired by Longhorn Steakhouse, a restaurant that makes a similar topping over their french onion and various other menu items. It provides the perfect crisp for this rich and homey soup.

Two crocks filled with french onion soup, topped with Swiss cheese and panko breadcrumbs.
Emilee Unterkoefler

5. Transfer your crocks onto a sheet pan (if you haven’t done so already) and place in the oven for about 10 minutes, or until the cheese and panko breadcrumbs begin to turn golden brown.

Two crocks of bubbly hot French onion soup fresh out of the oven and ready to be eaten!
Emilee Unterkoefler

6. Feast your eyes on the most scrumptious bowl of soup your heart could ever desire! All you need is a little salad or sandwich to accompany it! It’s the perfect dinner combo for a cool late summer evening.


We hope the steps for making caramelized onions will inspire you to pull out the old chef’s knife and get to work! While slicing an onion is one skill you’ll need, learning to make a uniform dice is important, too!

Emilee Unterkoefler Emilee Unterkoefler
Emilee Unterkoefler is a freelance food writer, hiking enthusiast, and mama with over ten years of experience working in the food industry. Read Full Bio »

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