Cut the cheese into slices. Drain cucumber cubes. Wash the dill, dab dry. Pluck and chop flags. Separate eggs. Beat egg whites with salt until stiff. Sift flour over it and fold in loosely with the egg yolks.
Heat 1 tablespoon of oil in a frying pan (approx. 24 cm Ø). Spread about half of the egg mixture in the pan. Bake until the underside is slightly browned. Spread approx. 1/2 of the cheese and 2 tbsp. cucumber cubes on one half of the foam mass.
Fold the omelette carefully.
Bake in the preheated oven (electric cooker: 150 °C/ convection oven: 125 °C/ gas: see manufacturer) for approx. 3 minutes. Remove from the pan, slide onto a plate and keep warm. Prepare the second omelette in the same way.
Cut the omelettes in half. Sprinkle the remaining cucumber cubes on top or add them. Sprinkle with dill and serve immediately.