In a large pot over medium heat, heat oil. Sauté onion, celery and ginger for about 10 minutes, or until very tender. Add potatoes, green beans, carrot, squash, water, bay leaf and salt. Simmer, covered, for 20 minutes.
Uncover soup. Simmer for 15 minutes longer. During the last five minutes, add peas, tomatoes, basil and thyme. Remove bay leaf before serving.
Per serving: 88 calories, 3 g protein, 17 g carbohydrates, 2 g total fat (0 g saturated fat), 0 mg cholesterol, 4 g fibre, 307 mg sodium.