Spread the tofu slabs out on a triple layer of paper towels and press with more towels to remove as much moisture as possible, which allows for a better sear.

Whisk the lime zest, lime juice, and fish sauce substitute in a medium bowl until combined. Toss in the carrots and cucumber and let the mixture sit for about 15 minutes, stirring occasionally, so the vegetables soften and absorb the flavors.

Mix the mayonnaise and sriracha in a small bowl until smooth and set aside.

Season the dried tofu with salt and pepper, then dredge each slab in cornstarch until evenly coated, shaking off the excess so the crust stays light.

Heat the vegetable oil in a large nonstick skillet over medium-high heat until the oil shimmers but does not smoke. Add the tofu and cook until golden brown and crisp on both sides, about 4 to 5 minutes per side.

Spread the spicy mayonnaise on the toasted rolls. Layer the crispy tofu slabs onto the rolls, top with the pickled vegetable mixture and cilantro leaves, and serve immediately while the tofu is still hot.