Heat the oil in a large skillet or wok over medium heat.
Add the onion, ginger, lemongrass, and garlic.
Sauté for 7 to 10 minutes, stirring occasionally, until the onions have softened and are just beginning to brown.
Add the crumbled tofu and chopped water chestnuts to the skillet. Use a spoon to break up the tofu into small crumbles.
Cook for 4-5 minutes, stirring, until everything is heated through.
Stir in the low-sodium soy sauce, hoisin sauce, and chile sauce.
Cook for another minute until the sauce has coated the filling and thickened slightly.
Transfer the mixture to a serving bowl.
To serve, arrange the lettuce leaves on a platter alongside small bowls of the tofu filling, grated carrots, green onions, fresh mint, and chopped peanuts.
Let everyone build their own wraps.