Whisk together the peanut butter, water, lime juice, sweet chili sauce, soy sauce, and Sriracha sauce (optional: brown sugar).
Toss the tofu and half of the chopped peanuts with the peanut sauce. Set aside.
Heat the oil in a pan over medium heat. Add the garlic and ginger. Cook for about 2 minutes, be sure not to brown. Add the pepper and carrot. Cook for another 2 minutes.
Add the cabbage and soy sauce, and cover the pan tightly with a lid. Cook for 2 minutes, until the cabbage just begins to soften.
Remove the vegetables from the heat and set aside to cool to room temperature. (Optional: Toss together with the green onions, cilantro, basil, and mint.)
Lay out the leaves of lettuce, combining two leaves if small by overlapping them.
Evenly divide the tofu mix between the lettuce cups then top with the sautéed vegetables (with or without the green onions, cilantro, basil, and mint).
Sprinkle with the remaining chopped peanuts and serve with a lime wedge.