Make the marinade: combine the soy sauce, brown sugar, olive oil, cider vinegar, ketchup and garlic powder in a bowl.
Pat dry the steak tips, and place in a large sealable plastic bag. Pour the marinade into the bag, and seal. Gently toss the steak in the marinade, then refrigerate.
Marinate the steak tips for at least an hour prior to cooking. Remove the steak from the fridge 30 minutes prior to grilling time to complete the marinating time and come closer to room temperature.
Preheat a grill to medium high. Take the steak tips out of the marinade bag, letting the excess marinade drop back into the bag. Place the steak on the grill, and cover.
Grill the steak tips for 4 minutes on one side, then turn and grill 4 minutes on the other side. This should get them to about medium rare, but check for doneness and cook for a couple more minutes if needed.
Remove steak tips to a platter, and cover loosely with foil. Let rest for 5 minutes before serving.