Heat 2 tablespoons of oil in a saucepan. Add onion and garlic and fry gently until golden.
Stir in chili powder, Curry Powder, water, peanut butter and brown sugar. Bring to a boil; simmer gently until thickened.
Stir in soy sauce and lemon juice, then salt and pepper.
Turn mixture into a serving dish. Preheat broiler. Grease a broiler pan.
Trim and cut meat in 1/2″ cubes. Thread (not too tightly) onto 8 bamboo skewers, leaving a space at each end for holding.
Cover ends with small pieces of foil to prevent burning.
Place skewers in greased broiler pan. Brush with remaining 1 tablespoon oil.
Cook under preheated broiler 10-15 minutes until golden and cooked through.
Turn and brush frequently with oil during cooking. Garnish with lemon pieces and cilantro sprigs, if desired, and serve hot with peanut sauce.