Copycat Chicken Lettuce Wraps

Make the sauce: In a small bowl, whisk together hoisin sauce, soy sauce, rice wine vinegar, Sriracha, and sesame oil. In a large skillet over medium-high heat, heat olive oil. Add onions and cook until soft, 5 minutes, then stir in garlic and ginger and cook until fragrant, 1 minute more. Add ground chicken and cook until opaque and mostly cooked through, breaking up meat with a wooden spoon.  Pour in sauce and cook 1 to 2 minutes more, until sauce reduces slightly and chicken is cooked through completely. Turn off heat and stir in chestnuts and green onions. Season with salt and pepper. Spoon rice, if using, and a large scoop (about 1/4 cup) of chicken mixture into center of each lettuce leaf. Serve immediately.