In pan, saute ground chicken in sesame oil until cooked through. Drain if mixture is watery.
Add shiitake mushrooms and onion; saute until mushrooms have softened and appear caramel colored.
Add garlic, ginger, hoisin, water chestnuts and green onions. Let chicken mixture simmer on low.
To make peanut sauce: In saucepan over medium-low heat, mix peanut butter, brown sugar, lime juice, chili garlic sauce, ginger and soy sauce until smooth, warm and thinned slightly.
Fold into chicken mixture. Stir until combined and simmer on low until peanut sauce is evenly distributed.
Garnish with fresh cilantro and crushed peanuts. Serve in lettuce wraps.