Chicken Wraps with Plum Sauce

Name: Chicken Wraps with Plum Sauce
Ingredients: 6 garlic cloves, smashed in a garlic press; 2 1/2 tablespoons (2 to 2 1/2-inch piece) peeled and diced fresh ginger; 3 teaspoons sesame oil; 1/4 cup packed dark brown sugar; 3 tablespoons unseasoned rice vinegar; 2 green onions, white and green parts separated, thinly sliced; 1 1/2 pounds ground chicken meat (I like using half thigh, half breast meat); 1/2 teaspoon dry mustard powder; 1/4 teaspoon ground white pepper; 1/8 teaspoon ground cloves; Red chili pepper flakes; 1 (8-ounce) can water chestnuts, drained and diced; 2 heads butter lettuce, leaves separated and washed