The original recipe comes from Harumi Kurihara. Using the scallops normally available in the US, I had some problems with amount of sauce in her original recipe and I altered to work better for me. The idea of combining hot food over chilled lettuce may sound unusual, but not so strange when you consider we have salads with grilled salmon or chicken on top in the US. You only need enough shredded lettuce to line the plate. If you do not have mirin, use sake or sherry.