Preheat oven to 350℉ (180℃).
Spray nonstick cooking spray on 1 ¾ qt casserole dish. In large nonstick skillet, over med heat, cook barley for 2 to 3 min until lightly browned - in sm amt of water or broth.
Place in prepared casserole dish.
In same skillet, cook onions and cauliflower, stirring frequently, 5 min.
Add mushrooms and carrots.
Cook 5 more min, stirring frequently.
Add veggies to casserole.
In a sm bowl, combine water, broth mix, garlic powder, and pepper.
Mix well and add to casserole.
Mix well, cover, and bake 1 hr 15 min, until barley is tender and most of the liquid has been absorbed.
Stir several times while baking.
Let stand 5 min, then mix and serve.