In a large skillet, heat oil over medium heat. Sauté tofu, mushrooms, onion, water chestnuts, and celery 2 to 3 minutes until soft.
Reduce heat to medium, and stir in cashews, teriyaki sauce, vinegar, and vegetable stock. Simmer 2 to 3 minutes.
Spoon tofu mixture into the center of each piece of lettuce leaf and drizzle with tamari or soy sauce, if desired. Wrap the lettuce around the filling and eat like a taco.
Packaged baked tofu was used in this recipe for ease and enhanced flavor. It also makes this a lower fat recipe (as opposed to frying the tofu). You can find this product in many grocery stores, Asian stores, and most natural foods stores.
The tofu filling is equally delicious in a corn or flour tortilla.