Combine the flour and garlic powder in a shallow dish and mix well. Coat the beef in the flour mixture. Brown the beef on all sides in the oil in a heavy saucepan. Stir in the beer and teriyaki baste. Bring to a boil; reduce heat.
Simmer covered, for 1 hour, stirring constantly. Stir in the potatoes, onion and pepper. Simmer, covered, for 45 minutes or until the beef and potatoes are tender, stirring occasionally. Remove from heat. Stir in the green onions.