The ultimate soup guide

I've always loved soup. It's my favorite comfort food. I love that it can be made with the finest, most expensive ingredients or last night's leftovers. 

Since I started culinary school, I appreciate it even more. I spent five hours every day for half a semester taking a class called Soups, Stocks, and Sauces. I learned the variety of ingredients, seasonings, and garnishes for soups is endless. 

I've been making "good soup" for years, but even I was surprised by how much better the soup I make now tastes after learning so much about it in school.

That said, I wanted to share my soup knowledge with you all. If you've ever wondered why restaurant soups taste so much better than the soups you make at home, this post is for you. 

Stock vs. broth

Stock and broth are very similar, but they are not the same. Stock is made by simmering bones, mirepoix (onion, celery, and carrots), and sachet d'épices (herbs / aromatics) in water for upwards of 6 to 8 hours. As the bones simmer, they release collagen and gelatin into the liquid, and it develops body and flavor. It isn't seasoned. 

Broth is made with meat, not just bones. The meat can still be attached to the bones, but it doesn't have to be. It is also made with mirepoix and sachet d'épices, but it is simmered for significantly less time—only about 2 hours. You can make broth with stock or with water. If you make it with water, it will be a lot thinner and it won't have as much body and depth of flavor. This is because there isn't enough time for the bones to release their collagen and gelatin. 

Also, broth is seasoned, and stock isn't. So broth is tasty by itself, whereas stock is not. Because stock isn't seasoned, it makes a better base for soups and sauces. 

In class, we made stock every day. We made white stock, brown stock, fish stock, and vegetable stock. If you want to make stock at home, you can save leftover bones in your freezer or you can purchase bones from a butcher. This may sound odd, but if you want to make the best stock, use chicken feet. They're very gelatinous. If you're in the Indianapolis area, I've seen them for sale at Asia Mart, which is an Asian grocery store on East 86th Street in the Castleton area.

If you prefer to buy stock, purchase a high-quality, low-sodium stock like Kitchen Basics or Swanson.

At first glance, the recipes for white stock, brown stock, fish stock, and vegetable stock look nearly the same, but there are a few big differences. I will include the stock recipes at the end of this post.

Mirepoix 

Pronounced meer-pwah, mirepoix is crucial for flavoring soups, stews, sauces, braised dishes, etc. When in doubt, start with mirepoix. Mirepoix is a mixture of 50% onions, 25% carrots, and 25% celery by weight. So if your soup has 8 ounces of onions, it should have 4 ounces of carrots and 4 ounces of celery. 

I get so incredibly frustrated with most recipes online because the measurements aren't listed by weight. Instead, it's written as 1 carrot, 1/2 diced onion, 2 stalks celery, etc. But vegetables come in all sizes, and your onion may weigh 12 ounces, whereas my onion weighs 6 ounces. So the only way to get consistent results is to measure ingredients by weight. That is why all of my recipes show ingredients' weights. The best thing you can do for yourself is get a scale to measure the weight of your ingredients! I own the Ozeri Pronto Digital Multifunction Kitchen and Food Scale. It's less than $12, and it works great.

Caramelizing vs. sweating

Before you add liquid to your soup or stock, you must sweat or caramelize the mirepoix. This is the first step in building the flavors of a dish.

To sweat mirepoix, cook it in a pot over low heat with butter or oil until everything softens and releases moisture. This helps to concentrate flavor. The flavor remains concentrated even when you add liquid to the pot later. No browning occurs when you sweat mirepoix. The flavor profile of the vegetables will not change.

As you probably guessed, when we caramelize mirepoix, we brown (but NOT burn) the mirepoix. When we do this, the "maillard reaction" occurs. When mirepoix is heated to 250 degrees Fahrenheit and above, the sugar breaks down and caramelizes. The sweetness of the vegetables deepens and intensifies, and the flavor profile changes.

To caramelize mirepoix, cook just the onions and carrots over medium low heat with butter or oil. As the vegetables cook, they will soften and release moisture. Once the moisture evaporates, the onions and carrots will start to caramelize. Make sure to stir every so often so it doesn't burn. When the onions and carrots are evenly brown, add the celery. Celery doesn't brown in the same way that onions and carrots do. Celery is low in sugar and has a lot of moisture, which can prevent the onions and carrots from adequately caramelizing. That's why it's added last. Once the celery softens, add your liquid to the pot.

We decide whether to sweat or caramelize mirepoix depending on whether we want the sweeter flavor. In my experience, it seems best to sweat mirepoix in recipes with white stock and caramelize mirepoix in recipes with brown stock, but this is not a rule of thumb.

Thickening agents

Soups can be thickened any number of ways. Traditionally, there are two kinds of thick soups: cream soups and purée soups. Generally, cream soups are thickened with a roux or other starch, whereas purée soups rely on a purée of the main ingredient for thickening.

A roux is equal parts by weight fat and flour. A roux is a good thickening agent because the starches in the flour expand to absorb the liquid. Gluten-free flours don't work well when making a roux because they don't have the same starches that flour with gluten has.

There are two ways to incorporate roux into a liquid without causing lumps: cold stock can be added to a hot roux while whisking vigorously, or room-temperature roux can be added to a hot stock while swhile whisking vigorously.

Cornstarch is a gluten-free thickening agent. Use it to make a slurry by whisking a tablespoon of stock into a tablespoon of cornstarch in a separate bowl and thoroughly mixing until there are no lumps. Then slowly pour the slurry into the stockpot. This is not a good thickening agent to use if you plan to freeze the soup.

Using heavy cream to finish a soup is another easy way to thicken it, however, it isn't the healthiest option.

Two other thickening agents I like to use that are healthier are cashew cream and pureed cauliflower. Make cashew cream by soaking 1 cup of raw, unsalted cashews in water overnight or at least 6 hours. Drain the cashews and dump them in the basin of a high-powered blender or food processor with 1 cup water. Blend on high until very smooth.

For pureed cauliflower, cut the florets from a head and boil them until they're very tender, or about 20 minutes. Transfer the cauliflower to the basin of a high-powered blender or food processor and blend on high until it's very smooth.

For both the cashew cream and the pureed cauliflower, stir them in the soup when it's almost done.

Boiling vs. simmering

This may seem like a no-brainer, but I think there is a common misconception as to what constitutes simmering versus boiling. 

When a recipe wants you to simmer the soup, it means cook the soup over medium-low heat as small bubbles and gently break the surface every once in a while. Boiling is done over high heat. You'll see lots of big bubbles over the surface of the soup.

You may be wondering why a lot of recipes ask you to "bring to a boil and reduce to a simmer." The answer is twofold: First, it can take a lot of time for soup to reach a simmer at medium-low heat, and second, you can control the temperature of your soup better if you know what its boiling point is.

Most of the time, it's best to cook your soup over a simmer. If you cook it at a boil, the ingredients in the soup will jostle around too much and break apart. Also, too much liquid will evaporate before the flavor can develop.

Sachet d’epices

Sachet d’epices is herbs and seasonings tied together with twine in cheesecloth. It's used to add flavor to soups, stocks and sauces. A standard sachet consists of peppercorns, bay leaves, parsley stems, thyme, cloves, and garlic. The amount of liquid determines the exact quantity of each ingredient.

Spices vs. fresh herbs vs. dried herbs

It is best to add spices and dried herbs to your soup toward the beginning so the flavor has time to develop and infuse the soup. I like to saute the spices and dried herbs with the other ingredients for about 30 seconds before adding the liquid. Stir fresh herbs into the soup right before serving it to maximize flavor. If you add fresh herbs too soon, the flavor will be subdued, and you'll lose all benefits of using fresh herbs.

If you need to substitute dried herbs for fresh herbs, use half the amount in the recipe. For example, if a recipe calls for 1 teaspoon fresh thyme, use 1/2 teaspoon dried thyme. This is because dried herbs have a much more concentrated flavor.

White stock

Yield: 1 gallon

Ingredients

• 1 pound mirepoix, small dice (8 ounces onion, 4 ounces carrot, 4 ounces celery)
• 7.5 pounds chicken bones, rinsed and cut into 3 to 4-inch pieces
• 1.5 gallons cold water
• 1 Sachet d’epices (1 bay leaf, 1/2 teaspoon dried thyme, 1/4 teaspoon crushed peppercorns, 4 parsley stems)

Equipment needed:

• Large stockpot
• Ladle
• Strainer
• Cheesecloth

Directions

1. Place the mirepoix in a stockpot and sweat until onion is soft and translucent.
2. Add bones to stockpot and cover them with cold water. No bones should be above the surface of the water.
3. Bring the water to a boil, skimming off the scum that rises to the surface. 
4. Reduce to a simmer and add sachet to simmering stock.
5. Continue simmering stock and skimming scum for 4 to 6 hours.
6. Strain stock with strainer lined with cheesecloth. Cool stock and refrigerate or freeze it.

Brown stock

Ingredients

• 7.5 pounds bones, veal or beef, rinsed and cut into 3 to 4-inch pieces
• 1.5 gallons cold water
• 1 pound mirepoix, small dice (8 ounces onion, 4 ounces carrot, 4 ounces celery)
• 1 Sachet d’epices (1 bay leaf, 1/2 teaspoon dried thyme, 1/4 teaspoon crushed peppercorns, 2 crsuhed garlic cloves, 6 parsley stems)
• 4 ounces tomato paste

Equipment needed:

• Roasting pan
• Large stockpot
• Ladle
• Strainer
• Cheesecloth

Directions

1. Place bones in roasting pan, one layer deep, and caramelize them in a 375°F oven for about 1 hour. Turn the bones occasionally to brown them evenly.
2. Remove bones and place in stockpot. Pour off the fat from the roasting pan and reserve it.
3. Deglaze the roasting pan with part of the cold water.
4. Add the deglazing liquor and the rest of the cold water to the bones, covering them completely. Bring to a boil and reduce to a simmer.
5. Add portion of reserved fat to roasting pan and sauté mirepoix until evenly caramelized. Add the tomato paste and continue cooking until the tomato paste and mirepoix are a deep brown color. Add the mixture to the simmering stock.
6. Add the sachet to the stock and continue to simmer for 4 to 6 hours, skimming as necessary. Strain stock with strainer lined with cheesecloth.
7. Cool stock and refrigerate or freeze it.

Vegetable stock

Yield: 1 gallon

Ingredients

• 2 fluid ounces vegetable oil
• 2 pounds mirepoix, small dice (16 ounces onion, 8 ounces carrot, 8 ounces celery)
• 1/2 pounds leeks, white and green parts, chopped
• 4 garlic cloves, chopped
• 4 ounces fennel, small dice
• 2 ounces turnip, diced
• 2 ounces tomato, diced
• 1 cup white wine
• 7.5 pounds chicken bones, rinsed and cut into 3 to 4-inch pieces
• 1.5 gallons cold water
• 1 Sachet d’epices (1 bay leaf, 1/2 teaspoon dried thyme, 1/2 teaspoon crushed peppercorns, 8 parsley stems)

Equipment needed:

• Large stockpot
• Ladle
• Strainer
• Cheesecloth

Directions

1. Heat oil in large stockpot. Add mirepoix, leek, garlic, fennel, turnip and tomato, and sweat for 10 minutes.
2. Add wine, water and sachet. Bring to a boil, reduce to a simmer, and cook for 45 minutes, skimming stock if necessary.
3. Strain stock with strainer lined with cheesecloth. Cool stock and refrigerate or freeze it.

Fish stock

Yield: 1 gallon

Ingredients

• 2 fluid ounces clarified butter
• 1 pound mirepoix, small dice (8 ounces onion, 4 ounces carrot, 4 ounces celery)
• 8 ounces mushrooms, sliced
• 10 pounds fish bones or crustacean shells
• 5 quarts water
• 1 Sachet d’epices (2 bay leaves, 1/2 teaspoon dried thyme, 1/4 teaspoon crushed peppercorns, 4 parsley stems)

Equipment needed:

• Large stockpot
• Ladle
• Strainer
• Cheesecloth

Directions

1. Sweat mirepoix in butter in large stockpot until soft and translucent, about 2 minutes.
2. Add mushrooms, fish bones, and water to stockpot. Bring to a boil, reduce to a simmer, and cook for 45 minutes, skimming stock if necessary.
3. Strain stock with strainer lined with cheesecloth. Cool stock and refrigerate or freeze it.