1. Place onions in a greased shallow roasting pan; top with brisket. Combine the ketchup, paprika and garlic powder; spread over brisket. Dissolve bouillon in hot water; pour into pan. Cover and bake at 325° for 1-1/2 hours.
2. Add the potatoes, carrots and celery. Cover and bake 1-1/4 to 1-1/2 hours longer or until meat and vegetables are tender.
3. Remove brisket to a serving platter; let stand for 10 minutes. Thinly slice meat across the grain. Serve with vegetables. Yield: 6 servings.