Soak mushrooms in warm water 20 minutes,drain,reserving 1/4 cup liquid. Squeeze out excess water. Discard stems ;slice caps. Combine reserved 1/4 cup mushrooms liquid. Chicken broth,ketchup,sherry,soy sauce,vinegar and sugar in small bowl. Set aside

Heat 1 teaspoon oil in large saucepan over medium heat. Add ginger and garlic; stir-fry 10 seconds. Add mushrooms,tomato and green onion;stir-fry 1 minute add chicken broth mixture;bring to a boil over high heat. Reduce heat to medium ;simmer 10 minutes

Combine 1 tablespoon water and cornstarch in small bowl;set aside. Heat remaining 1/2 tablespoon oil in large nonstick skillet over medium heat. Add zucchini and yellow onion;stir-fry 30 seconds. Add remaining 3 tablespoons water. Cover and cook 3 to 4 minutes or until vegetables are crisp-tender,stirring occasionally. Add tomato mixture to skillet. Stir cornstarch mixture and add to skillet. Cook until sauce boils and thickens.