1) Cut lamb into cubes and put into a shallow dish. 2) Mix together wine, olive oil, bay leaf, garlic, celery and basil. 3) Pour marinade over the meat and stir to coat. Cover, chill and leave to marinate for 1-2 hours. 4) Preheat grill. 5) Arrange meat, onions and tomatoes on 8 skewers. 6) Grill for 10-15 minutes, basting with marinade from time to time. 7) Turn over halfway through cooking time.