Dried mushrooms contain a high concentration of glutamic acid—nature’s version of MSG—so adding them to soups is a no-brainer. I love dried porcini mushrooms for the sweet, earthy flavor they add to soup. Dried shiitake mushrooms are great for soup as well; I find that the ones available at Asian markets tend to be of better quality than the tiny bags found in grocery stores, and they are loads cheaper. Either soaked and chopped, or just thrown whole into the soup pot to enhance the broth, dried mushrooms are powerhouses of umami flavor.