Combine mushrooms, onion, celery, carrots, garlic and margarine in a 2-quart casserole; microwave, uncovered at high for 6 to 7 minutes, stirring after 3 minutes.
4 cup mushrooms, 1/2 cup onion, 1/2 cup carrots, 1/2 cup celery, 2 cloves garlic, 2 Tbsp margarine