Wash scallops, remove roe. Pat scallops dry and cut in slices. Put scallops, water, lemon slice and bay leaf in a saucepan. Simmer gently 20 minutes. Strain, reserving liquid. Discard lemon and bay leaf. If necessary, add enough water to reserved liquid to make 1-1/4 cups liquid. Cook potatoes in boiling, salted water until tender. Drain and return to pan. Mash with 1 tablespoon of butter. Season with salt and pepper. Beat well; cool slightly. Transfer to a large pastry bag. Preheat broiler. Pipe potato around edges of 4 ceramic scallop dishes. Melt remaining butter in a saucepan. Add mushrooms, shallots and Curry Powder and cook 2 minutes. Stir in flour and cook 1 minute. Add reserved liquid and bring to a boil. Reduce heat and simmer 2 minutes, stirring constantly. Remove from heat and stir in scallops, cream, parsley, salt and pepper. Spoon into dishes. Broil 4-5 minutes or until lightly golden. Garnish with bay leaves, citrus twists and dill sprigs, if desired, and serve hot.