In a bowl, combine sugar, salt, garlic, red pepper flakes, pepper and olive oil and stir well to form a thick, fairly dry paste.
Rub the paste all over the steak and refrigerate, wrapped in plastic, for 12 hours or overnight.
Preheat the grill.
Remove the steak from the refrigerator and wipe off the excess marinade with a paper towel.
Cook on the hottest part of the grill for four minutes on one side then turn with tongs and cook three minutes on the other side.
Allow the steak tips to rest for three to five minutes.
Drizzle with the olive oil and the balsamic vinegar and serve immediately.