Slow Cooker Pepper Steak

Sprinkle beef with garlic powder.

Heat oil in a large skillet over medium heat. Add beef strips; cook and stir in batches until browned, 5 to 7 minutes. Transfer to a slow cooker.

Stir water and beef bouillon together in a small bowl until dissolved. Add cornstarch and mix to dissolve. Pour mixture into the slow cooker. Stir in tomatoes, onion, soy sauce, and sugar.

Cook on Low until flavors blend, about 6 hours, adding bell peppers during the last hour. Season with black pepper.