My brother-in-law is a soup aficionado. Loves to eat it and loves to cook it. Apparently in his earlier bachelor years before I knew him, he made a lot of soups and is now getting back into the swing of things. We've recently had a few chats about soup making and the other day he left a voicemail on my cell phone entitled "My food thoughts for the day".
1. "Starting a soup with a roux is a great way to add flavor and texture."
After the base of veggies, also known as a mirepoix or sofrito, have sauteed in the fat of your choice, add a couple tablespoons or so of flour. Let this cook until the flour has turned a light caramel colored brown. Then add your liquid and continue with the recipe.
Raw dry flour should not be added directly to a simmering soup. If you do this, you will probably get very unappetizing clumps of flour floating on top of the soup. The heat from the soup liquid makes the flour molecules bind to themselves instead of moving evenly throughout the soup. Starting with fat, as in a roux, allows the flour molecules to be surrounded by fat molecules, so that they are more easily incorporated into the liquid.
If you find yourself with a soup that's not as thick as you'd like, either make a roux on the side and add it to the simmering soup. Or make a slurry of equal parts flour and cold water in a separate bowl. Stir until homogenized and add this paste to the cooking soup.
2. "You have got to season things to make them taste good."
It's such a simple, yet essential concept. In order for food to taste good, the levels of salt and pepper need to be balanced properly. The only way to tell this is to taste, taste, and then taste again. Especially in a cooking preparation like a soup which has many layers and dimensions, it's important to season each level that you add. And then taste. Even if you are a strict recipe follower, salt and pepper amounts are subjective, and you shouldn't feel locked into someone else's taste preferences. There's nothing more disappointing to me then going to a nice restaurant that thinks so highly of themselves that there is no salt on the table; only to find yourself needing to amp up the flavor.
The need for salt in a human diet goes way beyond your food tasting good. Each cell in your body requires a proper balance of salts in order for healthy metabolic functioning. Our physiology is dependent on sodium.
I'm not advocating over-salting food just for the sake of your cells. But it's interesting to note the connection between our human need and craving for salt and the perception that food tastes "better" when it's properly seasoned. It's as if the salt is a catalyst unlocking the dimensional flavors of even the most bland foods.