Pesto soup is a popular Italian summer dish that typically consists of a traditional pesto sauce recipe that is then combined with fresh vegetables steeped in water or flavored broth. Some cooks prefer to use vegetable or chicken stock rather than water, although others believe these ingredients detract too much from the pesto flavor. Pesto soup can work well with any variety of vegetables; common choices are vegetables that are in season and which ones each cook likes the best. Various regional versions of pesto soup can also be made according to local food preferences. Freshly made basil pesto is a favorite addition to this recipe.
Recipes for pesto soup often use a variety of fresh vegetables such as carrots, zucchini, leeks, onions, cabbage, eggplant, and celery. Many home cooks also add potatoes and beans or green peas for some more nutrients. Fava beans and Great Northern beans are some favorite choices. The beans and vegetables generally need to be boiled until tender for this type of pesto soup. Since the vegetables such as the carrots and leeks take the longest to cook, they are often the ones that are steeped in the hot water first.
Many traditional Italian cooks recommend making the pesto in soup from scratch rather than purchasing it pre-made from the fresh condiment section in a grocery store. The pesto sauce made as a soup garnish is often made from ground walnuts or pine nuts, olive oil, garlic cloves, fresh basil leaves, and grated Parmesan cheese. The ingredients are usually mixed together in a food processor or blender, though some home cooks prefer to grind them by hand with a mortar and pestle. This process usually begins with mashing the oil, basil, and garlic into a paste before adding the nuts and cheese.
Other versions of pesto soup can be made in a slow cooker rather than a pot on the stove. These recipes often call for the pesto sauce to be blended further with the broth rather than kept on the top as a garnish. The vegetables and beans are first tenderized in the slow cooker while the cook prepares the pesto sauce and then stirs it into the rest of the mixture. Some cooks also prefer to add pasta such as angel hair or thin spaghetti to the soup as well.
