Add onion and garlic and fry gently until golden. Stir in chili powder, Curry Powder, water, peanut butter and brown sugar. Stir in soy sauce and lemon juice, then salt and pepper. Turn mixture into a serving dish. Grease a broiler pan.
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.