Heat oil in skillet or wok over high heat until sizzling. Quickly add onions, carrots, and broccoli. Stir fry for two minutes. Add squash and mushrooms. Simmer for 2 to 3 more minutes until crisp-tender. Add soy sauce, if desired. Salt and pepper to taste and serve at once. Makes 5 servings.
Note: Other vegetables may be substituted, such as snow peas, cabbage, zucchini,
or green beans.