In a large flat dish (something like an 8×8” baking dish), combine the soy sauce, oil, balsamic vinegar, garlic, smoked paprika, oregano, and black pepper. Whisk to incorporate.
Cut the tofu into ¼-inch-thick slices and add to the marinade one slice at a time, flipping the slice back and forth so both sides get coated. Set aside for 10 minutes.
Heat a large non-stick skillet over medium heat and cook the slices in a single layer until lightly golden on the bottom, 3 to 4 minutes. Then gently flip with tongs and cook the other side. Note: You’ll have to cook these in two batches.
Meanwhile, in a small bowl, stir together the mayo, sriracha, and chili powder.
When ready to make sandwiches, toast the bread.
To assemble a sandwich, slather one side of the toasted bread with the spicy mayo and mash a quarter of the avocado into the other side. Pile arugula, roasted red peppers, and 4 slices of tofu on one piece of the bread, and close the sandwich with the other. Eat immediately, or within a couple of hours.
