Cut the zucchini in half lengthwise, place cut side down, and slice into 5mm thick half-moons.

Pat the aburaage with a paper towel to remove excess oil. Cut it in half along the longer side, then cut diagonally into quarters.

Layer aburaage, canned tuna, and zucchini in a microwave-safe container. Add the seasoning ingredients (soy sauce and chicken stock powder). Cover loosely with plastic wrap and microwave at 600W for 2 minutes.