6 oysters, 3 tablespoons sake, 100ml mirin, 2 tablespoons soy sauce, 1T rice wine vinegar, 1 tsp wasabi powder, some rocket leaves, 1 lemon.
1. Add the mirin, vinegar, wasabi powder, soy sauce and sake to a bowl; Whisk till well mixed; Leave it for 2 hour.
2. Rinse rocket leaves and drain.
3. Rinse a lemon and drain; Cut into halves.
4. Scrub shells of oysters in running water; Wrap one hand in a clean dish towel and hold the oyster with the cupped shell down and the narrow hinged end towards you; Push the point of an oyster knife into the small gap in the hinge and twist it between the shells till the hinge breaks; Lever open the top shell; Slide the knife along the inner edges of the top shell and sever the muscle that joins the oyster to the shell; Lift off the top shell; Squeeze an half of the lemon for juice over the oysters.
5. Pour the sake mixture into serving glasses; Arrange the oysters on the top of the serving glasses; Garnish with the rocket leaves; Serve immediately.