Peel the oranges and grapefruit so that the white skin is also removed. Cut out the fillets between the parting skins, collecting the juice. Mix the fillets and juice. Season with sugar and cinnamon. Stir yoghurt and vanilla sugar until smooth
Separate eggs. Sift the flour, stir with the egg yolk and 1 pinch of salt until smooth. Beat the egg white until very stiff and carefully fold into the egg yolk mixture
Heat the fat in a large or 2 small pans. Add the egg mixture,
Arrange the foam omelette with fruit and yoghurt. Sprinkle with pistachios. Decorate with lemon slices and lemon balm if desired
Drink: apple juice