Separate eggs. Beat egg whites, salt and lemon juice until stiff. Carefully stir in the egg yolks. Sift the starch over it and fold in. Heat the fat in a pan and remove from the heat. Add the egg dough and smooth it down.
Sprinkle cheese over it. Cover the foam omelette and let it set at low heat for about 20 minutes. In the meantime, wash, clean and slice the mushrooms. Peel and finely chop the onion. Dice the ham. Heat oil in a pan. Brown the mushrooms and onion in it. Add ham and deglaze with cream and stock. Bring everything to the boil. Stir in sauce thickener. Season to taste with salt and pepper. Wash the chives and cut into fine rolls.
Brown the mushrooms and onion in it. Add ham and deglaze with cream and stock. Bring everything to the boil. Stir in sauce thickener. Season to taste with salt and pepper. Wash the chives and cut into fine rolls. Arrange omelette and mushroom and ham cream on a plate. Serve sprinkled with chives