Cut off the hard ends of the asparagus and trim off the harder scales near the bottom. Cut in half.Cut the kombu into an even number of pieces (2-4) to fit the container you’ll use to store in the fridge.
Add a pinch of salt to a pot of boiling water, then boil the asparagus for 1 minute. Drain and set aside til cool enough to handle.
Lay half of the kombu in your container to cover the bottom. Put the asparagus on top, then cover with the other strip(s) of kombu.
Cover with something heavy and leave in the fridge overnight. When ready to serve, sprinkle with salt (and a drizzle of olive oil if you like).