In a medium bowl, mix the sugar, soy sauce, pepper, garlic, lemon grass and sesame seeds. Place the meat in the dish and stir to coat. Cover and refrigerate for 4 hours.
Preheat barbecue for high heat. Discard marinade and thread meat onto skewers accordion style.
Brush cooking grate with oil, and discard marinade. Arrange skewers on the barbecue. Cook 5 minutes per side. Serve hot on skewers, or remove from skewers and serve on lettuce leaves. Garnish with coriander, mint, basil and sliced spring onions.