You can also make this recipe in a large saucepan on your stove top or in a slow cooker. The time is about the same; as soon as the vegetables are soft to bite, it's done. The thing I love about this soup is I can add a variety of vegetables, leftovers, and vary it based on what I have. If you don't have tomato paste, you can use tomato juice or sauce; just cut the amount of water down a bit, about a 1/4 to 1/2 cup less. I also use a lot of tomato paste but you can probably cut it in half for a thinner, lighter soup. Using tomato sauce or tomato juice will also thin it out.You can add cooked grain-free or gluten-free pasta to the soup at the end. Lentil pasta is grain-free. Add 1 to 2 cups of the cooked pasta once the soup is cooked.Feel free to top the soup with shaved or grated Parmesan cheese or another cheese on top when serving.You can use a bean other than a white bean, including lentils. If you're not eating beans, or want to reduce the carbohydrate count, leave them out and add some other vegetables such as cauliflower and butternut squash.