Slow-cooked omelettes such as frittatas or tortillas can sometimes be tough. The proteins in eggs, like those in meat, become leathery if overcooked. One way of creating a lighter-textured omelette is to souffle it.
6 eggs, separated
100g hard cheese, such as Gruyere or Cheddar, grated
A little salt, if you like (the cheese is salty)
Large knob of butter
Beat the egg yolks lightly, and fold in the grated cheese. Whip the whites. I do this with a hand whisk, until I get soft peaks when I lift the whisk from the egg. A little vinegar helps the process, apparently.
Fold the whites into the yolk/cheese mixture, turning it over repeatedly with a spoon until roughly amalgamated. (You do this gently, in order to retain the air bubbles in the egg.)
Melt the butter over a gentle heat in a heavy, non-stick, 28cm frying pan. Pour in the omelette mix, and cook until it sets on the bottom. Cook the top under the grill, at its lowest flame.