Rinse whole lettuce leaves and pat dry, being careful not tear them. Set aside. In a medium skillet over high heat, brown the ground beef in 1 tablespoon of oil, stirring often and reducing the heat to medium, if necessary. Drain, and set aside to cool. Cook the onion in the same pan, stirring frequently. Add the garlic, soy sauce, hoisin sauce, ginger, vinegar, and chile pepper sauce to the onions, and stir. Stir in chopped water chestnuts, green onions, and sesame oil, and continue cooking until the onions just begin to wilt, about 2 minutes. Arrange lettuce leaves around the outer edge of a large serving platter, and pile meat mixture in the center. To serve, allow each person to spoon a portion of the meat into a lettuce leaf. Wrap the lettuce around the meat like a burrito, and enjoy! Can also be served as a main dish with a side of fried or white rice.