Bring a saucepan of water to the boil over high heat. The depth of the water needs to be half the height of the heatproof cups you are using.

Mix 2 lightly beaten eggs, 400 ml (14 fl oz) chilled Basic Dashi Stock, 2 teaspoons soy sauce and a large pinch of salt. Strain the egg mixture into a bowl.

Divide 8 peeled and deveined king prawns (shrimp), 2 thinly sliced shiitake mushrooms and 230 g (8 oz) wilted English spinach (excess water squeezed out) among four heatproof cups and pour in the egg mixture. Top with 8 matchstick strips of lemon zest. Cover each cup with foil and seal tightly.

Turn down the pan of boiling water to medium heat. Gently place the cups in the pan, cover with a lid and steam for 5 minutes. Turn off the heat and set aside for 15 minutes without removing the lid from the pan. Serve immediately.