Lay 400 g firm tofu flat on a chopping board, place one hand on top to hold it in place and hold your knife parallel to the chopping board. Make a horizontal cut through the middle, trying your best to keep them the same thickness.
Wrap each piece with kitchen paper and place on microwavable plate. Microwave for 1 min 30 seconds at 600W.
Remove the kitchen paper and sprinkle both sides of each piece with 4 pinches ground black pepper.
Heat a large frying pan on medium and add 1 tbsp olive oil. Once the pan is hot, evenly coat both sides of each piece of tofu with a thin layer of 2 tbsp potato starch and immediately place them in the pan.
Fry until the underneath is crispy and golden, then flip and repeat on the other side.
While the tofu is cooking, mix the 1 ½ tbsp soy sauce, 1 tbsp mirin, 1 tbsp sake, ½ tsp grated ginger root and 1 tsp grated garlic in a small bowl to make the sauce.
Once both sides are browned, turn down the heat to low/medium-low and pour the sauce into the pan. Move the tofu around so that the sauce sticks to the surface, flip and repeat until the sauce is thickened and the tofu is evenly coated.
Dish up and sprinkle with 1 tbsp finely chopped green onions and 1 tsp chili threads (optional).
Enjoy!