In a medium bowl or small baking tray, mix the corn flour and spices together. Add the water and mix until smooth. Set aside.
In another bowl, place the panko bread crumbs and set aside.
On a flat surface, place the nori seaweed. Arrange the tofu squares on top of the seaweed. Using a sharp knife or scissors, cut around the tofu. The nori seaweed should stick nicely to the flat side of the tofu. If the nori hangs over the sides of the tofu just trim off the excess and repeat with all four slices.
Place a small frying pan with a lip of at least 1.5 inches over a medium low heat. Add around 1-2 cm of vegetable oil to the pan and slowly bring up to temperature.
Dunk a piece of tofu into the corn flour batter, flip it over and dunk the reverse, making sure the whole piece is coated and being careful not to remove the nori. Then dunk the battered slice of tofu into the panko breadcrumbs, flip over and dunk again. (You may need to press some panko into the tofu using your fingers - just make sure the whole slice is covered in panko). Repeat with the other slices of tofu.
Drop a pinch of breadcrumbs into the oil to make sure it’s hot (they should sizzle nicelthen, using tongs, pick up one slice of tofu and lay it carefully into the hot oil. Fry for around a minute on each side then remove from the oil and place on some kitchen towel to drain. Repeat with the other slices.
Place a slice of tofish on the 4 slices of bread which are topped with lettuce. Top the tofish with some pickled onions and the second slice of bread. Serve immediately.