Chef John's Chicken Lettuce Wraps

Combine chicken, water chestnuts, mushrooms, yellow onion, 1/3 cup green onion, 1 tablespoon soy sauce, ginger, and 2 teaspoons brown sugar together in a bowl. Pat mixture down, cover bowl with plastic wrap, and refrigerate until ready to use.

Whisk chicken stock, vinegar, garlic, ketchup, 1 tablespoon soy sauce, sesame oil, 2 teaspoons brown sugar, pepper flakes, and dry mustard together in a bowl until glaze well-mixed.

Heat vegetable oil in a heavy nonstick skillet over high heat. Add chicken mixture; cook and stir until chicken no longer looks raw, about 2 minutes. Add 1/2 the glaze mixture; cook and stir until chicken begins to caramelize and brown, 10 to 15 minutes.

Reduce heat to medium-low. Pour remaining glaze into chicken mixture; cook until heated through and slightly reduced, about 3 minutes. Stir in cilantro, basil, and 1 1/2 tablespoons green onion. Transfer chicken mixture to a bowl; serve with lettuce leaves as wrappers.