Preheat the oven to 400°F and line a large baking sheet with parchment paper. Shred the super-firm tofu using the large holes of a box grater.
Add the shredded tofu to a large bowl and toss with the olive oil, soy sauce, nutritional yeast, onion powder, garlic powder, smoked paprika, salt, and black pepper. Spread into an even layer on a large parchment-lined baking sheet.
Bake for 25 minutes, tossing halfway through, until the tofu is golden and crispy around the edges.
Toss the baked tofu with ⅓ cup BBQ sauce until evenly coated. Add more if needed, but avoid adding so much that the tofu is swimming in sauce. Return to the oven for 5 minutes.
Make the ranch by stirring together the vegan mayo, lemon juice, jalapeño, garlic powder, onion powder, salt, pepper, parsley, and dill. If needed, add ½-1 teaspoon plant-based milk to thin it slightly. But it is very important to keep the ranch thick.
Carefully char the ears of corn directly over the flame of a gas stove, turning with tongs until charred in spots. Allow to cool slightly, then cut the kernels from the cob. For the pan method, cut the kernels from the cob first and cook them in a hot, dry pan until browned and lightly charred.
Make the slaw by thinly shredding the cabbage with a sharp knife or mandoline. Add it to a bowl with the charred corn, green onions, cilantro, lime juice, lime zest, and olive oil. Season with salt and black pepper and toss just before assembling the sandwiches.
Slice the ciabatta loaf in half lengthwise and lightly toast. Spread a layer of BBQ sauce over the bottom half, then pile high with the shredded BBQ tofu.
Top with the charred corn slaw, pickled red onions, and a generous drizzle of jalapeño ranch.
Close with the top half of the ciabatta, then carefully cut into 4 large sandwiches or 6 smaller sandwiches and serve!