
To a large skillet, add the oils, chicken, and cook over medium-high heat until chicken is cooked through; stir intermittently to crumbly while cooking.
Add the onion, hoisin sauce, soy sauce, rice wine vinegar, chili garlic sauce, stir to combine, and cook for about 5 minutes, or until onion is soft and translucent and most of the liquid has been absorbed; stir intermittently.
Add the garlic, ginger, stir to combine, and cook for about 1 minute, or until fragrant.
Add the water chestnuts, green onions, salt and pepper to taste, and cook for about 2 minutes, or until tender. Taste filling and make any necessary flavor adjustments, i.e. more soy sauce, hoisin, pepper, etc.
Spoon about 1/4 cup of the mixture into the lettuce leaves to serve.