Prep the lettuce and veggies. Separate and rinse the lettuce leaves.
Pat dry and keep chilled. Dice the onion, bell pepper, and mushrooms. Mince the garlic and ginger.
Slice the green onions, keeping the whites and greens separate.
Stir together the sauce. In a small bowl, whisk soy sauce, hoisin, rice vinegar, honey, sesame oil, sriracha, chicken broth, and cornstarch until smooth. Set aside.
Cook the aromatics. Heat oil in a large skillet over medium-high heat. Add onion and the white parts of the green onion.
Sauté 2–3 minutes until softened. Stir in garlic and ginger; cook 30 seconds until fragrant.
Brown the chicken. Add ground chicken. Break it up with a spoon and cook 4–6 minutes until no longer pink.
If there’s excess moisture, let it evaporate so the meat can lightly brown.
Add the veggies. Stir in bell pepper, mushrooms, and water chestnuts. Cook 3–4 minutes until tender-crisp. Season with a pinch of salt and pepper if needed.
Pour in the sauce. Give the sauce a quick stir and add it to the skillet.
Simmer 1–2 minutes, stirring, until it slightly thickens and coats the chicken and veggies.
Finish and taste. Remove from heat. Stir in the green parts of the green onion. Taste and adjust—add more sriracha for heat, vinegar for brightness, or a drizzle of honey for balance.
Assemble. Spoon the chicken mixture into lettuce leaves.
Top with chopped peanuts, cilantro, sesame seeds, and a squeeze of lime. Serve immediately.