Season the scallops with the salt, pepper and garlic and then lightly dust with flour. Heat the oil in a small frying pan. Briefly fry both sides of the scallops until sealed on the outside, but still rare in the middle. Take the pan off the heat and remove the scallops.
Add the white wine and then the miso, mirin, soy sauce, sugar and water to the pan and stir. Return to the heat and bring to the boil, stirring, then remove. Mix in the grain mustard and double cream.
Tear the leaves off the watercress and arrange on a large plate. Chop the stems finely and set aside as a garnish. Place the scallops on the bed of watercress leaves, pour the hot sauce over and garnish with finely chopped watercress stems. Sprinkle with Parmesan cheese and serve.
Recipe from Harumi's Japanese Cooking, By Harumi Kurihara, Published by Conran Octopus ltd.