1/2 pound fresh mushrooms, sliced
1 (8 ounce) can sliced water chestnuts, drained
1 small onion, halved and sliced
1 medium carrot, cut into 1/4-inch slices
1 celery rib, cut into 1/4-inch slices
2 tablespoons butter or stick margarine
1 1/2 pounds uncooked medium shrimp, peeled and deveined
1 cup sour cream
1/2 cup plain yogurt
1/4 teaspoon pepper
Hot cooked rice