Transfer the cups to a preheated steamer and cook over a high heat for 2-3 minutes. Turn the heat down to low, and cook for a further 15 minutes. Remove cups from the steamer, and garnish with yuzu citron rind. Wash clams well, rubbing the shells against one another. Slit leek lengthways, remove the hard core and cut into fine julienne strips.
Place clams in a frying pan, add sake, cover and heat on high.
When the clams are open, season with light soy sauce. Serve the clams with the pan juices, and garnish with leek. This simple steamed chicken dish is a great hot-weather favourite. Mix the sake, soy sauce and salt together and pour over the chicken. Marinate for 20 - 30 minutes.