In large heavy saucepan with cover heat oil over medium-low heat; add onion and garlic and cook 1 minute. Add cloves and, if using , ham; cook 5 minutes. Add lentils and stock and heat to boiling. Reduce to simmer and cook, covered, 30-40 minutes or until lentils are tender but retain their shape. Remove pan from heat, add bulgur and stir well. Uncover; add vinegar, parsley, scallions, salt and pepper. Fluff mixture with fork and serve either hot or cold.