Use a fork to poke holes all over the surface of the steaks and place steaks in a large baking dish.
In a bowl mix together beer, teriyaki sauce and brown sugar. Pour sauce over steaks and let sit about 5 minutes. Sprinkle with 1/2 the seasoned salt, pepper and garlic powder; set aside for 10 minutes. Turn steaks over, sprinkle with remaining seasoned salt, pepper and garlic powder then continue marinating for 10 more minutes.
Remove steaks from marinade. Pour marinade into a small saucepan bring to a boil and cook for several minutes.
Lightly oil the barbecue grate. Barbecue steaks for 7 minutes per side or until cooked to your liking. During the last few minutes of cooking baste steaks with boiled marinade to enhance the flavour and ensure juiciness.