In a large soup pot, heat 2 Tblsp olive oil. Add the following ingredients, all chopped: 1 large sweet onion, 4 or 5 green onions, 2 carrots and 2 celery ribs. Cook until the vegetables are tender, about 5-10 minutes.
Add 12 cups of water, 1 large potato cut into small pieces, 3 diced tomatoes, 1 Tblsp salt and a large pinch of saffron. Bring to a boil, reduce heat, cover and simmer for about 30 minutes.
While the soup is cooking, mix 2 cups of fresh basil, 2 garlic cloves and 1/2 cup of extra virgin olive oil in a food processor and blend until it forms a paste. Pour into a bowl and mix in 1/3 cup grated Parmesan cheese. This is a pistou, which differs from a pesto only in that it does not contain pine nuts. Set this aside for later.
When the 30 minutes are up, add one drained can of great northern beans, white kidney beans (cannellini) or navy beans, 1 cup of frozen or fresh green beans (cut into bite-size if using fresh) and half a pound of your favorite pasta (broken into small pieces if using spaghetti or linguine). Return to a boil, reduce heat, and simmer until the pasta is done (check the package, usually about 8-12 minutes).
Stir the pistou you made earlier into the soup and add 1 tsp of fresh ground pepper.
Serve immediately, or let it sit for a little while. The flavor improves as the soup sits. This soup is very light and is great for hot summer days. It's also extremely good for you as it contains only a fairly small amount of salt and is lacto-vegetarian.