Drain the tofu and pat dry. Slice into ½-inch thick slices. Arrange in a shallow dish (a square baking pan works great!). Whisk together marinade ingredients (excluding pepper) in a small bowl or measuring cup. Pour over top of the tofu. Season generously with black pepper. Marinate for 30 minutes in the refrigerator. After 15 minutes, flip the pieces.
Cut the radish and carrots into matchsticks and slice the cucumber and jalapeño. Add the radish, carrots, cucumber, and half of the jalapeño to a jar or glass container. Add water, vinegar, sugar, and salt to a small saucepan and warm over medium heat. Whisk frequently until most of the sugar and salt dissolve. Let cool for just a minute, then pour over the veggies. Let sit in the fridge for 15 minutes (or up to a week).
Prepare the spicy mayo by mixing together the mayo and sriracha in a small bowl.
Heat 2 tablespoons oil in a large skillet over medium heat. Once warm, add the tofu to the pan and let sit, frying for 5 minutes without moving or wiggling the tofu. Reserve the leftover marinade in the dish. After 5 minutes, flip the pieces carefully, then cook for another 5 minutes. Once done, flip a final time and cook 1-2 minutes. Remove from the heat and transfer to a paper towel-lined plate. Brush remaining marinade over both sides of the tofu.
While the tofu cooks, slice the baguettes down the middle lengthwise, being careful not to slice them completely in half. (You can slice in half, but it makes it a little messier to eat!) Pop them in the toaster oven to toast slightly, if desired, or leave them as is.
Assemble the banh mi. Spread mayo onto both sides of the baguettes, add desired amount of fresh jalapeños, add 2-3 pieces of tofu to each, then top with pickled veggies. Feel free to drizzle any extra mayo or marinade onto the sandwiches to make them extra juicy!