The Reason You Shouldn't Taste Soup Right After Adding Spices
Even if you're following a recipe, tasting as you go is important, no matter what type of soup you're making. Perhaps it'll still need more salt, could use a bit of heavy cream, or isn't as spicy as you hoped it would be. Naturally, you'd go ahead and add more seasoning as needed, grab a spoon, and have another taste. This may seem like the most obvious way to go about it, but apparently there's a right and a wrong time to taste soup, and it should never be right after you add spices.
In a Reddit thread asking professional chefs to share their best cooking tips, one user responded with some helpful advice about adding dry herbs and spices to soup. The self-identified chef explained that it's important to wait at least 15 minutes after you add any seasoning before you go ahead and taste the soup again. The reason for this is that spices release flavor into the soup gradually. If you taste your soup too early, you might make the mistake of adding more because it still tastes too bland — and an over seasoned soup can be just as bad as an under seasoned one, and maybe harder to fix.
It's better to add spices in the middle of the cooking process
Because it'll take some time for any spices and herbs to infuse your soup with flavor, Taste of Home says it's better to add them much earlier on in the cooking process, as opposed to at the end. The same applies to salt, too. It's important to salt your food in general, but salt also has the benefit of extracting more flavor out of whatever vegetables or other ingredients you may have added to your soup. If you add the salt and all the seasoning when the soup is already in its last stages of cooking, you're not giving it enough time to intensify.
Another seasoning tip from Self is that some spices are activated by heat. The heat of the simmering broth alone can accomplish this just fine, but if you really want to taste them in your soup, the outlet recommends "blooming" or sautéing spices in a pan before adding them in. This causes them to become more fragrant, and when you eventually taste your soup, the flavors will be much more robust.
So taste frequently, but not too early; season throughout the cooking process; and consider blooming your spices for the best soup you've ever made.