Dashi
The Japanese stock: kombu drawn out below a simmer, then katsuobushi steeped off the heat and strained without pressing.
Method
Wipe the 8 g kombu over with a dry cloth, leaving the white bloom on the surface: that is where much of its flavour sits. Put it into a pan with the 500 ml water and leave it to steep for 30m.
Bring the pan up very slowly over 10m, aiming to hold it around 60 °C. Lift the kombu out as soon as the first fine bubbles climb the sides and well before the water simmers: kelp held at the boil turns the stock slippery and faintly bitter.
Bring the liquid to a boil, take the pan straight off the heat and scatter in the 15 g katsuobushi. Leave it for 4m, until the flakes have all sunk.
Pour it through a sieve lined with muslin and let it drip for 3m. Do not press or squeeze the flakes: that forces bitterness and cloudiness into a stock whose entire point is clarity.