Heat olive oil in a saucepan over medium high heat. Add in ground chicken and cook, breaking into small pieces, until browned, about 5 minutes. If you have excess moisture or fat feel free to drain a bit.
Add in onion, garlic, ginger, soy sauce, rice wine vinegar, hoisin sauce and Sriracha. Stir until all of the chicken is thoroughly coated. Continue cooking for 1-2 minutes or until chicken is cooked and onions have become translucent.
Stir in water chestnuts and green onions until tender, about 1-2 minutes; season with salt and pepper, to taste. Stir in red chilli flakes.
Transfer the chicken to a bowl. Spoon the chicken mixture into the lettuce leaves. Enjoy!