Prep the lettuce: Gently separate and rinse the lettuce leaves.
Pat dry and chill in the fridge so they’re crisp when serving.
Mix the sauce: In a small bowl, whisk soy sauce, oyster sauce, rice vinegar, sesame oil, sriracha, and honey. If using hoisin, add it now. In a separate cup, stir cornstarch with water.
Chop the aromatics and veggies: Dice onion, bell pepper, and mushrooms.
Mince garlic and ginger. Slice green onions thinly. If using carrot or water chestnuts, finely dice.
Cook the chicken: Heat oil in a large skillet over medium-high.
Add ground chicken, breaking it up with a spatula. Season lightly with salt and pepper. Cook until no longer pink, about 5–6 minutes.
Add aromatics: Stir in onion, garlic, and ginger.
Cook 2–3 minutes until fragrant and the onion softens.
Stir in veggies: Add bell pepper, mushrooms, and any optional carrot or water chestnuts. Cook another 3–4 minutes until tender-crisp.
Sauce it up: Pour in the sauce and toss to coat. Stir in the cornstarch slurry and simmer 1–2 minutes until slightly thickened and glossy.
Adjust seasoning—more soy for salt, more vinegar for brightness, more sriracha for heat.
Finish and garnish: Remove from heat. Stir in green onions. Sprinkle with sesame seeds if you like.
Assemble: Spoon the warm chicken mixture into chilled lettuce leaves.
Add a squeeze of lime and a little cilantro if desired. Fold and eat immediately.