In a large nonstick skillet, saute the onion, celery, green pepper, mushrooms in oil until tender; add garlic, cook 1 minute longer. Stir in the tomatoes, water, rice, soy sauce, parsley, salt, paprika, cayenne, chili powder and pepper.to a 2-1/2-qt. baking dish coated with cooking spray.
Cover and bake at 350° for 65-70 minutes or until rice is tender and liquid is absorbed. Top each serving with 1 tablespoon sour cream.