Make the Sauce: Whisk together hoisin sauce, soy sauce, rice vinegar, ½ tbsp sesame oil, ginger, garlic, and shallot.
Cook Chicken: Heat 1 tbsp sesame oil in a skillet over medium-high heat. Add ground chicken, season lightly with salt and pepper, and cook until browned, breaking it apart.
Add Veggies: Stir in water chestnuts, mushrooms, and green onions. Cook for 3–4 minutes.
Combine: Pour the sauce over the chicken mixture. Stir well and cook another 2–3 minutes until slightly glazed.
Assemble: Spoon the filling into crisp lettuce leaves. Serve immediately and enjoy!