Make a brine of water and salt (not listed in ingredients) to the salinity of sea water. Put the clams in a colander and set it inside the brine so that they are slightly sticking out above water level.
Cover with newspaper, then let sit for about 2 hours to degrit. If it's warm inside the house, degrit them in the refrigerator.
Once they are finished degritting, rub the clams together while rinsing under running water, then blot excess water.
Put the clams in a heat-resistant dish, then add the sake and salt (if you prefer a light taste, go lightly on the salt).
Wrap in plastic wrap, then microwave for 2 minutes at 600 W. They are done when the clams open up. Don't be surprised, as they will make a loud noise when they open!
They should open after 2 minutes...but if they don't microwave for a while longer while keeping your eye on them.
Story Behind this Recipe
I love sake steamed Manila clams!! I wanted to make them easily in the microwave.
For the brine, 3% salt will give the same salinity as sea water. If you have 500 g water, you would add 15 g salt. It should taste a bit salty. The newspaper is used since clams will degrit only if it's dark, and also, they squirt out water. If you microwave them for too long, the clams will become tough.