In a large bowl, whisk together flour, cornstarch, and egg. Add 2 Tbsp water and whisk to combine. Add more water 1 Tbsp at a time until the batter is workable and there are no clumps left. Season with salt and pepper.

In a wok or deep pot, heat oil to 375 f, or until the oil is shimmering.

Wrap each piece of ahi lengthwise in a piece of nori seaweed. Measure the ahi against the seaweed first. The edges should match up- if the seaweed is too long, cut it to size with kitchen shears or a sharp knife.

Once you have wrapped the ahi, dip your fingers in water and run the water on the edge of the nori, then continue rolling it to stick the edges together.

Dip each ahi block wrapped in nori first in the tempura batter, making sure to coat the whole thing, including the ends, and then in the panko crumbs. Add to the hot oil immediately. Fry the fish till it is golden brown, only 30 seconds each, for a raw centre. Personally, I think this is the prettiest and most delicious way to eat Katsu, but if you want the fish to be fully cooked in the centre, fry it for a minute to a minute and a half.

Transfer the katsu to a cutting board and slice each block into about 10 pieces, each ¼ inch thick.

Sprinkle microgreens on a wooden platter(or a leaf like in the photo!), and arrange the katsu slices leaning on each other in a row, centres exposed.