Boil about 1 litre of water and 1 tsp salt.

Parboil the spinach. Dip in the stem part first and hold the leaf part with your hand or chopsticks/tong out of the boiling water for 30 seconds then place the leaf part into the boiling water and cook for a further 30 seconds.

Take out the spinach. Dip it into a bowl of icy cold water to avoid the spinach cooking further.

Squeeze out excess water and cut spinach 4-5 cm lengthwise.

Squeeze out excess water again and place spinach into a flat, shallow container.

Mix Dashi stock, soy sauce and mirin. Pour over the spinach to soak the spinach.

Cover with cling wrap and refrigerate for at least one hour.

Serve in a small bowl or plate and top with bonito flakes or roasted sesame seeds.