Food for Thought: Cooking With Onions

From the lecture series: The Everyday Gourmet — Cooking with Vegetables

By Chef Instructor Bill Briwa, The Culinary Institute of America

The interesting thing about the allium family is that as you travel around the world and you began to understand the flavors of the global kitchen, cooking with onions, or alliums, is a foundation in almost every cuisine. If you need a way of understanding how important they are, there’s a wonderful quote that can help you understand that: “What garlic is to salads, insanity is to art.”

Image of onions for an article on cooking with onions

Alliums are a foundational flavor in almost every cuisine around the world. The flavor of the world’s kitchens would be much less compelling if there were no alliums. Stir-fry dishes would fall flat. Mole sauces would be insipid without roasted garlic and roasted onions to lend complexity and grit. Cooking with onions is as fundamental as learning how to boil water!

This is a transcript from the video series The Everyday Gourmet: Cooking with Vegetables. Watch it now, Wondrium.

Onions or Alliums can be understood in two distinct groupings – dry and green.  Among the Dry you will find white, yellow, red and torpedo onions as well as a variety of sweet onions, shallots, pearl onions and Garlic.  These vegetables will be hard and firm with a dry papery husk.  They keep relatively well in a cool, dry environment.

  • Very firm to hard, dry, uniform in shape and size with small necks and papery outer scales
  • Reasonably free from sunburn spots, insect damage or any other surface blemishes
  • No thick, hollow woody centers/cores
  • No soft necks, strong onion aroma, bruising, sprouting, mold, water-soaked spots, or translucent, slippery layers (freezing injury)

Learn more about what you can do with cabbage, the king of the brassica family

Green onions as the name suggests are harvested fresh and immature.  This grouping includes scallions, leeks, Ramps, scapes, and spring onions and green garlic.

  • Tender, crisp, vibrant green tops with firm, white shanks or bulbs
  • Uniform in size and shape, well formed, (high ratio of white shank to green top) free from excessive roots that are relatively clean and moist
  • No crushed or broken leaves
  • No cracked, dehydrated root ends or soft bulb or shank ends
  • Free from slime, wilt, mold, discoloration or yellowing tops

Learn more about the unique properties of mushrooms including flavor and textural variances

In cooking, many compounds break down, others combine, and some evaporate off. Many of these changes cause changes in taste. Two families of vegetables that change dramatically with cooking are onions and members of the genus Brassica. When onions cook, some of their strong sulfur compounds dissolve, break down, and many evaporate making them milder and more pleasant or even sweet tasting.

Onion Soup

Make a Hearty Onion Soup


  • 2 Tbsp Olive oil 2 .
  • 3 large Yellow onions thinly sliced
  • Pepper
  • Salt
  • 1/3 Cup White wine
  • 2 quarts Chicken Broth
  • 2 tsp Thyme 2 tsp.
  • 1 Tbsp Sugar .
  • 1/2 Lemon juice
  • 6 slices Rye Bread thin
  • 1 1/2 Cups Gruyere grated

Cooking Instructions

  1. In a large saucepan, warm the olive oil over medium heat. Add the onions, pepper and salt. Cook over low heat, partially covered, stirring occasionally, until well caramelized – 30 to 40 minutes – until they turn a mahogany color. In this amount of time, they develop a tremendous amount of flavor, and the harsh, sulfurous quality of the onion has been driven off. The onion is now sweet and caramelized.
  2. Remove the onions and deglaze the pan with white wine, which provides acidity. You want the raw flavor of the wine to pass off, so reduce it until it’s almost dry (au sec in French).
  3. While the wine is reducing, add bay leaves and branches of thyme.
  4. Once the wine has reduced, add sugar and chicken stock to the pot and let it simmer so that the onions can give up their flavor to the broth. Once the pot comes up to a boil, reduce it to a simmer and wait about 20 or 30 minutes. As it comes up to a boil, you may discover some foam or scum floating on the top. Because you want a clear broth, skim the foam off with a ladle and discard it.
  5. After 20 or 30 minutes, retrieve the bay leaf and the branches of thyme. Then, taste it. Because there is a lot of sweetness due to the sugar and the natural sweetness from the onions, make sure that you season the soup properly with salt and black pepper—about six times as much salt as pepper.
  6. To add acid, squeeze in a few drops of lemon.
  7. If not using right away, cool to room temperature and refrigerate.
  8. While the soup base simmers, trim the bread to fit into individual soup bowls about 5 “across. Place the trimmed bread on a baking sheet and toast in the oven until golden – about 10 minutes. Remove from the oven and set aside. If making ahead, cool and store in a sealable plastic bag at room temperature.
  9. About 15 minutes before you want to serve the soup, preheat the oven to 400 degrees. Gently reheat the onion soup base over medium heat. Season again with lemon juice and salt if needed. Remove from the heat.
  10. Fill oven-proof soup bowls with the soup. Top with 1 crouton and grated gruyere. Carefully place the soup bowls onto a baking sheet and transfer to the oven. Bake until the soufflé is well risen and golden brown – about 20 minutes. Serve immediately.

Learn more about fruits that masquerade as vegetables

Recipe Notes

If you find that onions make you cry, store them for a few hours in the refrigerator to get them cold. Wear swim goggles, or turn on the fan in your kitchen.

When cutting onions, start with a cutting board. Use a paring knife to cut off both the root end and the stem end and then to help you peel the onion. Unfortunately, an onion is round and wants to roll all over the board. Take a chef’s knife and cut it in half through the stem end and the root end so it sits flat. Then, cut it into slices by turning it 90 degrees to get pieces that are all the same size.

If you’re using dried herbs instead of fresh herbs, use about a third as much of the dried herb as you would the fresh herb. This is because the moisture has been taken out of the dried herbs and they have shrunken, so you don’t need as much of them

Common Questions About Cooking with Onions

Q: What onion is the very best for cooking?

There are many types and flavors of onions, but the white part of any onion is good for cooking. The best onion for cooking is the one that is right for the dish.

Q: What makes onions so widely used in cooking?

Onions add a specific flavor and a small amount of sugar to a dish. Alliinase is an enzyme released when onion cells are broken that also creates a chain of flavor compounds that increase the flavor of a dish cooked with onions.

Q: Is it ok to eat onions raw?

Onions can be delicious when eaten raw and are often preferred raw for certain dishes.

Q: What onion is the healthiest to eat?

The healthiest onion, according to studies, is the red onion. The red onion contains a high level of anti-oxidants, fiber, and blood-thinning properties.

This article was updated on 1/13/2020

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