Heat oil in a large pan over medium heat. Add onion, celery and ginger. Sauté until very tender, 10 minutes. Add green beans, potato, carrot, squash, 8 cups (2 litres) water, bay leaf and salt. Simmer, covered, 20 minutes.
Uncover soup. Simmer 15 minutes. For the last 5 minutes, add peas, tomato, basil and thyme. Remove bay leaf. Serve.
To turn Summer Garden Soup into a main dish for lunch or a light supper, stir in small pieces of ham or cooked chicken, turkey or lamb just before serving.
The vegetables for Sweet Vegetable Soup can be cooked alongside a meat main dish. Meat needs a longer oven time, so the soup can be prepared while the meat finishes. Leave the meat to rest on top of the oven while you serve the soup.