In a skillet, heat up both oils over medium heat. Add chicken and cook until done.
Add chopped onion and minced garlic and cook for 4 to 5 minutes or until the onion is almost translucent.
In a small mixing bowl or measuring cup, whisk together hoisin sauce, soy sauce, sesame oil, vinegar, ginger and sweet chili sauce. Pour mixture over chicken and stir well.
Simmer over medium-low heat for 5 minutes.
Add chopped water chestnuts to chicken and stir. Remove from heat.
Place up to 1/4 cup of mixture onto each lettuce leaf. Serve immediately.
If you don't have ground chicken on hand, you can slice boneless skinless chicken breast into slices, partially freeze it (20 to 30 minutes in the freezer should do it), then pulse in the food processor until you reach desired texture.
If you don't like or have chicken on hand, you can also make this recipe with ground turkey or beef.
Please note, that the nutrition value can vary depending on what product you use. The information below is an estimate. Always use calorie counter you are familiar with.