Remove shells from the shrimp, leaving the tail sections on, and butterfly the shrimp by slicing them down the back, not quite in half. Rinse well and remove the dark vein from each. Drain and pat dry. Place the shrimp on a platter in one layer Heat the oil in a wok or skillet; add the garlic. Lower the heat and cook about 10 minutes, stirring constantly, until the garlic turns brown. Raise the heat, add the scallions and cook 30 seconds. Add the light soy sauce, rice wine and sugar and stir for 30 seconds. Place the dish with the shrimp into a steamer and cover each shrimp with a teaspoon of the garlic mixture. Cover and steam the shrimp for 6 minutes. Serve immediately.