Drain the oil from the canned tuna using a sieve. Press down to remove as much oil as possible.

Heat a pan over medium heat and add the drained tuna. Stir-fry to evaporate the moisture.

Once the tuna starts to change color, add soy sauce, mirin, and sugar. Mix well and continue stir-frying over medium to low heat.

Reduce the heat to low and continue stir-frying until the tuna becomes dry and you hear a crackling sound.