Knead together the beef, onion, pepper, garlic and salt and pepper. Let stand 30 minutes to blend flavors. Form into 16 oval balls. String 4 on skewers alternating with a onion quarter, green pepper quarter and cherry tomato on each skewer.Grill about 5 minutes until browned, turn and grill other side. Served with spiced brown rice and a large piece of the flat Afghan bread.