Wash the spinach thoroughly.

Wrap the washed spinach in plastic wrap.

Microwave the wrapped spinach for approximately 1.5 minutes at 500W or until wilted. Alternatively, use a 'boiled vegetable' auto-setting if available.

Drain the oil from the canned tuna.

Combine the drained tuna, soy sauce, mirin, and sesame oil in a bowl.

Squeeze out the excess moisture from the microwaved spinach.

Cut the spinach into 4-5 cm pieces.

Add the spinach to the seasoned tuna mixture.

Mix well to combine.

Serve immediately or chill for later.