The Science of Soup


Vegetable soups, both pureed and chunky, are simple to make. They’re prepared in two stages. First, cook the vegetables slowly in a little butter or oil until tender, then add the liquid to make the soup.

The preliminary cooking is important. Just think of the difference in taste between a boiled and a sauteed or roasted vegetable and you’ll get the point. Boiled vegetables are most like the vegetable in the raw state. Sauteed or roasted vegetables develop both softness and rich flavor. In most cases, cooking with a little fat brings out flavors that cannot be achieved by boiling or steaming. Greens and other non-root vegetables need this preliminary cooking to break down the cellulose walls so that the flavor of the vegetable is released. Root vegetables, such as carrots, turnips or beets, have a lot of sugar in them and must cook for a long time to release and even to caramelize their sugar.

The following onion soup requires caramelizing the onions to give them their rich color and sweet flavor. Using a heavy copper or cast-iron pan will help you perform this task properly, caramelizing--not burning--the onions.


Bean soups require a different approach. Beans lose their fresh sweetness when they are dried, taking on a mellow flavor, so it is traditional to cook them with herbs and spices and something salty, like bacon, a ham hock or, for those who don’t eat pork products, smoked chicken or turkey. The base of aromatic vegetables--onion, carrot and celery--needs to be strong or the soup will taste like porridge.

When you prepare main-course soups, the broth can be less intensely flavored because “meal-in-a-pot” ingredients, meat and vegetables, add flavor and should remain the focus.


1/4 pound pancetta (Italian bacon), finely diced

1 medium onion, finely diced

1 small carrot, finely diced

2 celery stalks, thinly sliced

1 teaspoon finely minced garlic

1 cup dried white beans

4 cups low-sodium chicken broth

1 teaspoon chopped fresh thyme leaves or 1 teaspoon dried

6 large leaves Swiss chard

Salt, pepper

Grated Parmesan cheese

Place pancetta in oven-proof pan over medium heat and cook, stirring occasionally, 2 minutes. Add onion, carrot, celery and garlic and cook, stirring occasionally, another 7 minutes, or until vegetables are tender.

Add beans, broth and thyme. Cover tightly. Bake at 350 degrees 1 1/2 hours or until beans are tender.

Meanwhile, remove center stems from chard leaves and cut into crosswise 1/4-inch slices. Coarsely chop leaves and add to bean mixture along with stems. If soup seems too thick, add some water. Return to oven and bake another 20 minutes.

Remove soup from oven and season to taste with salt and pepper. Serve very hot with grated Parmesan on side. Makes 5 to 6 servings.



1/4 cup unsalted butter

4 medium onions, sliced (about 8 cups)

4 cups veal stock or low-sodium beef broth

1/8 teaspoon freshly grated nutmeg

1 (12-ounce) bottle dark beer

1/2 pound sharp Cheddar cheese, crumbled

1/2 teaspoon salt

Freshly ground pepper

Melt butter in 3-quart, heavy pan over low heat, preferably cast iron or copper. Add onions and cook, covered, 15 minutes.

Uncover and continue to cook 30 to 40 minutes, stirring frequently, or until onions turn deep golden color. Add stock and nutmeg. Cover and bring to boil. Reduce heat and simmer 15 minutes.

Bring beer to boil in small pan over medium heat. Boil until reduced by half. Remove from heat and add cheese, stirring until melted. Transfer mixture to blender. Add 1 cup onion soup and blend until smooth. Reserve.

Remove onion mixture from heat and strain, reserving liquid. Transfer onions to blender or food processor and puree until very smooth. Return puree to pan. Add reserved liquid and cheese mixture. Add salt and season to taste with pepper. Serve very hot in tureen. Makes 5 servings.


1/4 pound bacon, cut in 1/4-inch dice

1 cup dry white wine

1 1/2 pounds boneless, skinless chicken breasts, cut in 1-inch strips

12 jumbo shrimp, peeled and deveined

5 cups fish stock or chicken broth

1 tablespoon finely minced garlic

2 teaspoons finely minced onion

1 teaspoon celery seeds

1 teaspoon anise or fennel seeds

3 sprigs fresh tarragon, leaves only, chopped, or 1 tablespoon dried

2 cups broccoli florets

3/4 cup milk


Freshly ground pepper

2 tablespoons unsalted butter

Cook bacon in large, heavy pan or Dutch oven over low heat 2 minutes without browning, stirring frequently. Add white wine. Increase heat to high. Bring liquid to boil and cook 1 minute to burn off alcohol.

Add chicken, shrimp, fish stock, garlic, onion, celery seeds and anise. Reduce heat to medium. Add tarragon if using dried. Cover and cook 3 minutes. Add broccoli and milk and cook, uncovered, another 2 minutes. Season to taste with salt and pepper.


To serve, use slotted spoon to transfer bacon, chicken, shrimp and broccoli to soup bowls. Return broth to boil and add butter. Remove from heat and, if using fresh tarragon, add now. Serve soup in tureen and ladle into garnished bowls at table. Makes 6 servings.