Heat olive oil in a saucepan over medium-high heat.
Add ground chicken and cook, crumbling with a wooden spoon.
Stir in the onion and cook on medium heat for 3-5 minutes, until translucent.
Add the garlic and ginger and cook until fragrant, 1-2 minutes.
Stir in the hoisin sauce, soy sauce, rice wine vinegar, sriracha and water chestnuts; cook 3 minutes.
Season with salt and pepper, to taste.
To serve, spoon several tablespoons of the chicken mixture into the center of a lettuce leaf, top with green onions.
