Remove the tofu from the packaging, then drain the water and press the tofu for at least 30 minutes. While the tofu presses, stir the marinade ingredients together in a small container or bowl.
When the tofu has finished pressing, cut the tofu block into four slabs by slicing lengthwise, parallel to the widest sides to maximize surface area.
Plate the tofu slabs into a shallow dish and pour the marinade over it. Let the slabs soak for about 30 minutes (Note 1), occasionally turning the pieces and spooning the marinade over them.
While the tofu marinates, stir the sauce ingredients together in a small bowl.
Prepare your dipping stations. Place the dredging flour into one bowl. Whisk the batter ingredients together in a second bowl. Stir the breading ingredients together in a third bowl.
Add oil to a medium nonstick skillet, getting it about ¼ inch deep. Place the skillet over medium-high heat to begin heating up the oil.
When the oil starts to shimmer, remove one of your tofu slabs from the marinade. Gently shake off any excess liquid, then dip the slab into the bowl of flour, getting it lightly coated on all sides. Dip it in the batter next, again getting it well coated, then dip it in the breading.
Carefully place the coated tofu slab into the skillet of hot oil. Repeat the dipping process, adding as many tofu slabs as you can fit without crowding. I like to cook two at a time. You can cook the remaining slabs in a second batch, adding oil to the skillet if needed. Cook the tofu for 3 to 4 minutes on each side, until golden brown and crispy. Move them to a wire rack to drain when they're done frying.
Optionally, cut each tofu cutlet into thin slices. Serve over rice and cabbage with tonkatsu sauce and a sprinkle of toasted sesame seeds and chopped scallions.