In a very large skillet heat oil over medium-high heat. Add onion, white part of green onions, and garlic; cook and stir for 3 minutes. Add green beans; cook for 2 minutes more, tossing with tongs frequently. Add water; bring to boiling; reduce heat. Simmer, covered, for 7 to 9 minutes or until beans are crisp-tender. Stir in basil, salt, and pepper. Serve with tomato wedges. Makes 4 servings.