2 tablespoons light soy sauce
1 tablespoon hoisin sauce
2 tablespoons clear rice vinegar
1/2 teaspoon salt
1/2 teaspoon sugar
3 tablespoons vegetable oil
2 cloves garlic, minced
2 teaspoons minced fresh ginger
1/3 cup minced red onion
1 cup chopped canned button mushrooms
1/2 cup water chestnuts, minced
1 pound boneless, skinless chicken breasts, minced
8 to 10 inner leaves iceberg lettuce, edges trimmed and chilled
Handful of fresh cilantro leaves, coarsely chopped
1/4 cup unsalted roasted cashews, coarsely chopped
Combine the soy sauce, hoisin sauce, rice vinegar, salt, and sugar in a small bowl and mix together until the sugar dissolves.
Heat 1 tablespoon of the oil in a wok over high heat. Stir-fry the garlic and ginger for 10 seconds. Add the onion, mushrooms, and water chestnuts and stir-fry for 2 minutes. Remove the contents of the wok.
Heat the remaining 2 tablespoons of oil in the wok. Swish the oil around, add the chicken, and brown for 1 minute, or until no longer pink. Add the cooked vegetable mixture back to the wok, decrease the heat, and stir in the sauce mixture. Stir for 1 minute, or until the sauce is heated and the chicken is cooked through.
Spoon the filling in equal amounts into the lettuce cups. Top each lettuce cup with cilantro and sprinkle with chopped cashews. Serve warm.