mirin (substitute rice vinegar, if you can't find)
Preheat oven to 375 degrees F and cover a baking sheet with foil.
Drizzle chicken thighs with 1 tablespoon olive oil, and season with kosher salt and pepper. Set on covered baking sheet and roast in oven for 20 minutes.
While the chicken is cooking, soak mushrooms in a medium bowl of hot water, covered, until soft, about 20 minutes. Remove chicken from the oven, debone, and chop into medium-size pieces.
Add 1 tablespoon olive oil to a large pan and sauté onion over medium heat until soft, about four minutes. Add ginger, and sauté for one more minute. Add chopped chicken to the pan until cooked through, about two minutes.
Remove mushrooms from water, finely chop, then add to the pan with the chicken. Add mirin, soy, and oyster sauce and stir-fry for two minutes. Remove from heat. Mix in green onions and water chestnuts.
Spoon chicken mixture into lettuce cups and sprinkle with cilantro.
Photography and styling by Julia Gartland