Bring a saucepan of salted water to a boil, then add the beans and cook for 3-5 minutes until bright green and tender, but still firm to the bite. Drain and rinse in cold water then plunge into iced water to set their colour.

Bring the sake to a boil in a small saucepan and then trnsfer to a small bowl and combine with the sugar and shoyu.

Place the dashi in a saucepan with 1 tablespoon of the sugar, sake and shoyu mixture and bring to a boil. Drain the beans and add them to the dashi. Return to a boil then remove from the heat and cool.

Heat a frying pan to hot and add the sesame seeds, tossing them in the pan constantly until they are golden.

Transfer the toasted seeds to a mortar and pestle, a small food processor bowl or a spice gringer and grind them to a coarse paste.

In a bowl, combine the sesame seeds with the remaining sake, sugar and shoyu mixture (about 5 table spoons) and the sesame oil. Then toss through the drained beans.