Asian Beef Lettuce Wraps

INGREDIENTS

• 16 leaves boston bibb lettuce
• 1 lb lean ground beef
• 1 tablespoon cooking oil
• 1 large onion, chopped
• 2 fresh garlic cloves, minced
• 1 tablespoon soy sauce
• 1/4 cup hoisin sauce
• 1 teaspoon ground ginger
• 1 tablespoon rice wine vinegar
• 1 (8 ounce) can water chestnuts, drained and finely chopped
• 1 bunch green onion, chopped
• 2 teaspoons sesame oil (dark)