Create one layer of beef pieces on a plate and sprinkle with garlic powder. Continue with more layers until all beef is seasoned. In a large skillet or Dutch oven over medium, heat oil for 1 minute. Add beef to cover bottom of pan. Turn pieces while cooking to brown all sides then transfer to slow cooker. Repeat until all beef is browned.
In small cup add soy sauce and beef bouillon. Stir to dissolve the bouillon. Pour liquid over beef in slow cooker. Add tapioca, onion, bell peppers, tomatoes and pepper to the slow cooker. Stir to combine. Cover and turn on timer on high for 3 hours or low for 6 hours.
Serve over rice or noodles if desired.