Prepare the sauce: Whisk together soy sauce, hoisin, rice vinegar, brown sugar/honey, and sriracha in a small bowl. Set aside. Mix cornstarch with 1 Tbsp cold water in another small bowl for later thickening.
Prep ingredients: Make sure everything is chopped super fine – this is key to the authentic Yard House Chicken Lettuce Wraps texture.
Cook aromatics: Heat avocado oil in a large skillet or wok over medium-high heat. Add diced onion, white parts of green onions, garlic, and ginger. Sauté 2–3 minutes until fragrant and onion is translucent.
Brown the chicken: Add ground chicken. Break it up with a wooden spoon and cook until no longer pink, about 5–6 minutes.
Add vegetables: Stir in diced shiitake mushrooms and water chestnuts. Cook another 3–4 minutes until mushrooms soften.
Pour in sauce: Give the sauce another whisk and pour over the chicken mixture. Bring to a simmer.
Thicken: Stir the cornstarch slurry once more, then pour into the pan. Cook 1–2 minutes until sauce is glossy and coats the chicken beautifully.
Finish: Remove from heat. Stir in sesame oil and green onion tops. Taste and adjust seasoning – more sriracha, soy, or sugar if desired.
Serve: Spoon warm filling into lettuce cups. Top with crushed peanuts, extra green onions, cilantro, and a squeeze of lime if desired. Serve immediately with extra sauce on the side.