Cut steak into 2 inch strips and sprinkle with garlic powder. Heat oil in a large skillet over high. Brown beef for about 1 minute and add to slow cooker.
Thoroughly whisk cornstarch into broth and add to slow cooker along with undrained tomatoes and soy sauce. Cook on high for 3-4 hours (low for 6-8 hours).
Approximately 30 minutes before beef is done, slice onion and peppers and add to slow cooker.
Meanwhile, cook rice as directed on package.
Serve steak and peppers over rice with orange wedges on the side.