This is a mini version of a soup my grandmother used to cook when we were kids.  You can make it non fat by eliminating the olive oil:  Lowfat White Bean Soup with Rosemary and Parmesan

In 1 tsp olive oil, saute:
1 yellow onion chopped
1/2 carrot chopped
1/2 celery stalk chopped

then add 1/2 cup cooked white navy beans
1/2 tsp dried rosemary
2 cups chicken or vegetable stock or water
1 tbsp diced tomatoes if you like
1 tsp sea salt
Coarse ground black pepper

Cook for 20 minutes, then stir in:
A shake of lowfat parmesan cheese
1/2 cup fresh chopped parsley