Heat olive oil in a large skillet or wok set over medium-high heat. Add the onions to the heated oil and cook for 3 to 4 minutes or until softened. Stir in the garlic and ginger, and cook for 20 seconds.
Add ground chicken and continue to cook for 6 to 8 minutes or until opaque and no longer pink. Break up the meat with a wooden spoon while cooking.
Meanwhile, in a mixing bowl whisk together the hoisin sauce, soy sauce, rice vinegar, hot sauce, and toasted sesame oil.
Pour the sauce into the skillet and stir to combine; cook for 2 minutes or until the sauce reduces slightly and the chicken is cooked through. Remove from heat.
Stir in the chestnuts and green onions. Season with salt and pepper; taste and adjust.
Spoon the chicken mixture into the center of each lettuce leaf, garnish with green onions, and serve.
Notes
Chicken Lettuce Wraps: These lettuce wraps are prepared with ground chicken, but you can also use ground pork, ground beef, ground sausage, and so on.
Lettuce: The best wraps to use are sturdy head lettuces with thicker ribs on their leaves, which should be deep enough to hold the filling. Bibb lettuce is a good choice.
Water Chestnuts: If you can't find water chestnuts, you can use thinly sliced jicama.
Hot Pan: Ensure the wok or pan is hot to avoid steamed chicken.
Thicker Sauce: For those who like a thicker sauce, add 1/2 tablespoon of brown sugar to the sauce.