Drain the tofu piece for 20 minutes. Place it on a plate and place a heavy plate on top to compress it.
Meanwhile, combine the rice vinegar, water and sugar in a small saucepan over medium heat and stir until the sugar is completely dissolved. Remove from heat and add the carrots and daikon. Let sit for at least 1 hour, preferably overnight.
Cut the piece of drained tofu into about 24 small slices. In a small bowl, combine the tofu pieces with soy sauce, root ginger, lemongrass and garlic. Marinate for at least 30 minutes.
In a bowl, stir mayonnaise, sriracha and pepper. Set to one side.
Heat a little sesame oil in a frying pan. Remove tofu from marinade and fry tofu till golden and crisp on each side.
Cut the baguette lengthwise without separating top and bottom. Remove the inside and cut baguette into 4 equal pieces. Spread the bottom part with spicy mayonnaise.
Top with tofu slices, marinated vegetables, coriander, and cucumber sticks. Add chopped peanuts and a few drops of soy sauce (optional) and serve at once.