Some General Rules to Make Any Soup You Want
It's fall, and during the fall and winter I like to make nice soups and curl up in front of a movie. I will probably do that later today.
Soups are probably my favorite thing to cook. They are incredibly easy to make and there is so much room for creativity. I'll publish some of my favorite recipes later, but in this hub I'm going to just explain the basic steps for making soup.
As a general rule of thumb all soups start with miripoix. "Miripoix" is a mix of diced celery, carrots, and onions. Cajun soups like gumbo start with "trinity," a mix of diced celery, green peppers, and onions, or miripoix substituting green peppers for carrots. Both trinity and miripoix are available pre-diced in the frozen vegetable section of the grocery store. The dice of your miripoix depends on the type of soup that you are making. For example: if I were making a cream of mushroom soup I would use a very fine dice because I would not want my celery, carrots, and onions to be very noticeable in my final soup. In a vegetable soup, however, I might want to use a larger dice. The dice of your miripox is really your first judgement call.
Note: If you are making a soup with meat that should be seared you should sear the meat before you start sweating the miripoix.
Generally speaking the first step in any soup is sweating your miripoix over medium heat. This requires a pinch of salt and some type of oil. I tend to render bacon to get oil for most of my soups, though I will use vegetable oil or butter depending on how I want my soup to taste. I also tend to add minced garlic and diced jalapenos to my miripoix during this step. Once the onions are translucent you can start adding other ingredients.
If you are making a bisque or thick cream soup you need to make a roux. A roux is a basic method for thickening liquids. It is half fat and half flour (by weight). You render your fat (or in the case of making a soup it already has been rendered) and then add your flour stiirring well. The roux flour will clump up and then will loosen slightly. When the flour loosens your roux is finished and you can thicken any liquid. You can make your roux separately and add it back to your soup later to thicken it, or it can be made in the same pot as the miripoix after the miripoix has sufficiently sweated. A general rule of thumb is when you combine roux and liquid, one should be cold the other should be hot. So if you make your roux separately allow it to cool in a refridgerator before adding back to your hot soup.
If I am making gumbo I always make my roux separately. A gumbo requires a cajun roux. A cajun roux is just roux that has been allowed to cook until it is the color of chocolate. It is tricky to do. It needs to be stirred constantly and has to be pulled from the heat at just the right moment before it burns. (I'll write a gumbo recipe later).
After you have sweated your miropoix (and made a roux if desired) you can start adding your other vegetables in order from what takes the longest to cook to what takes the least amount of time to cook. If you have made your roux in the same pot as your miripoix you should add your liquid at this point. If not you can wait. For some soups like cream of mushroom and cream of broccoli I'll wait to add my liquid to give the mushrooms, or broccoli time to cook.
At this point you should add your liquid. Cream soups are usually half heavy cream or milk and half some type of stock. If you decide to use milk make sure that you don't let the soup boil as the milk will curdle and the texture of your soup will be ruined. Water can always be a liquid as well, but water will tend to dilute the flavor. Bring the temperature of the soup up and use the liquid to continue cooking your ingredients. When the soup is hot you can add chilled roux to thicken it, or use a slurry, or cold water mixed equally with corn starch.
When the soup is hot, all the ingredients are cooked, and it is as thick as I desire, I taste it to make last minute adjustments, adding salt and pepper as needed. This is when I will add any herbs that I want to add like basil in tomato basil. This is also when I will add any cheeses. (Cheeses need to be melted into an already thickened soup to avoid clumping) Some soups like lentil benefit from a last minute addition of some type of acid. Usually I will use lemon juice, but I have even used distilled vinegar. Acidity will lighten your soup, but it will curdle homogenized milk.
Making soups is really just a simple process to follow. All soups follow this process, though some tweak the process more than others. Some basic steps will improve any recipe. Miripoix doesn't change the flavor of a soup so much as give it a really good foundation to build your flavors on. Soups can be thickened with either starch or roux. (Potatoes will also thicken a soup if you allow them to cook long enough and In my opinion, roux gives a better texture to the final soup.) Vegetables should be added so that the longer cooking vegetables have a longer time to cook. The process for making soup allows a lot of room for adjustment depending on your tastes.