For the potato souffle from the steamer, separate the eggs, whisk the egg whites with the sugar.
Mix yolks, curd cheese and lemon zest. Carefully fold in beaten egg whites.
Grease ramekins with butter, sprinkle with sugar and pour in curd mixture.
Cover with foil, place on the cooking plate of the steamer and cook the curd souffle for 20 minutes at 90°C.