Preheat oven to 350'F. Lightly oil a 1 3/4-quart casserole or spray with nonstick cooking spray. Melt 1 tablespoon of the margarine in a large nonstick skillet over medium heat. Add barley and cook 2-3 minutes, stirring frequently until lightly browned. Place in prepared casserole. Melt remaining margarine in skillet. Add onions and cauliflower. Cook, stirring frequently, 5 minutes. Add mushrooms and carrots. Cook 5 more minutes, stirring frequently. Add vegetables to casserole. In a small bowl, combine water, broth mix, garlic powder and pepper. Mix well and add to casserole. mix well, cover and bake 1 hour and 15 minutes, until barley is tender and most of the liquid has been absorbed. Stir several times while baking. Let stand 5 minutes, then mix and serve. In each serving: 135 calories, 4 grams protein, 4 grams fat, 21 grams carbohydrates, 268 milligrams sodium, zero cholesterol.