Mix brown rice vinegar and sugar. Either let sit until sugar dissolves, or heat on stovetop or in microwave to dissolve faster. Place julienned carrot in mixture. Let sit overnight.
Sriracha Mayo
Add all ingredients to a small bowl. Whisk.
Marinated Tofu
Add sesame oil, tamari, and sriracha sauce to a large shallow dish. Whisk.
Drain and press the tofu. If you don't have a tofu press, place the tofu in between a clean kitchen towel. Place a heavy object, like a cast iron skillet on top. Let sit 15 minutes.
Slice tofu into 6 long strips. Place in the marinade. Marinate for at least an hour.
Place tofu slices on a large pan. Cook over medium heat until golden brown on both sides.
Sandwiches
Toast the buns. For a better bun to filling ratio, scoop out some of the bread - especially the top bun if it's larger than the bottom bun.
Slather sriracha mayo on buns. Layer tofu, sliced cucumber, pickled carrots, cilantro, and jalapeño on top.
Notes
*If you like to slather both pieces of bread with sriracha mayo, you'll want to double the sriracha mayo recipe. Store each component of the sandwich separately. Then assemble when ready to eat. Store the ingredients in air-tight containers in the fridge.Tofu will last up to 5 days in the fridge. Pickled carrots will last up to 2 months in the fridge. Sriracha mayo will last up to 2 weeks.