Preparation :
Wash and dry the mushrooms thoroghly, trim the stalks. Slice the green pepper into rings, pell the tomatoes, scoop out their seeds and cube. Peel the lemon and slice in thin layers.
Melt the margarine over moderate heat, when it starts to sizzle add the mushrooms and pepper, stir continuously for 2 minutes. Add the tomatoes and salt and stir for one or more minutes. Add the wine and cook for one more minute. Remove the pan from the heat, add cream and stir. Place the sea bream in a deep pan and pour the tomato sauce over. Place the sliced lemon and bay leaf on top, cover and cook for 20 minutes on moderate heat. Serve.