Onigiri

Rinse the rice in cold water 5–6 times, until the water runs clear, and let it drain in a sieve for 20–30 minutes.

Cook the rice in a rice cooker or in a covered pot (with a rice-to-water ratio of about 1:1.1) until tender; after cooking, let it cool slightly so it stays warm but doesn't burn your hands.

Drain the tuna in a sieve and press out the liquid well, mash it with a fork, and mix with mayonnaise and soy sauce until smooth — this is the filling.

Moisten your palms with cold water and rub them evenly with salt — it's the salt, not vinegar, that gives onigiri its flavor and helps the rice keep longer (vinegar is used to season sushi rice, not onigiri).

Place about 100 g of warm rice on a moistened palm, make a well in the center, add 1–2 tsp of filling, and cover with a small portion of rice on top.

Rotating the ball between your palms, shape it into a firm triangle or ball, pressing the rice gently so the onigiri holds its shape and doesn't fall apart.

Cut the nori into strips and wrap them around the base of each onigiri, leaving a small corner of rice exposed if desired.

Serve right away while the nori is still crisp, or wrap the onigiri in plastic wrap without the nori and add the sheet just before serving.