Corn, fresh green beans, peas, carrots, onion, celery, zucchini, summer squash, fresh spinach, or kale all work great in this soup. I like to use a bag of frozen mixed veggies since it's easy to keep in the freezer and it gives a healthy variety of veggies with no washing and chopping. If you are using fresh veggies in this soup, wash and dice them and saute them in olive oil until they are tender before adding the tomatoes, then follow the instructions for the remainder of the soup. Fresh veggies will need to be sauteed to soften them and bring out the flavor. If you are using onions, be sure to add those first since they take a little longer to cook than the other veggies. If you want to add spinach, do so at the end of cooking.