Score meat by making shallow cuts at 1 inch intervals diagonally across the steak in a diamondpattern; repeat on other side of meat. Place meat in a resealable plastic food bag. Stir together lemon peel, lemon juice, sugar, soy sauce, oregano and pepper. Pour over meat and close bag. Marinate in the refrigerator for 2 hours or overnight, turning bag occasionally.
Prepare grill for medium heat. Drain meat, reserving marinade. Grill steak on uncovered grill directly over medium coals 12-14 minutes for medium doneness, turning once and brushing occasionally with reserved marinade. Discard any remaining marinade. To serve, thinly slice meat across the grain.
Nicole's Note
Bring marinade to a boil before brushing over steak as you are grilling it. If you don't boil it, you run the risk of brushing raw meat bacteria over cooked food - if you don't have it on the grill long enough after brushing the marinade on, you could contaminate your food.