Heat 2 tsps at a time of oil or butter over a medium heat in a large non stick frying pan. Ladle in half of the egg mixture and swirl the pan to distribute evenly. Cook for one minute or so, until just set, then fold over in half and gently cook for a further 30 seconds to one minute, until just set in the middle. Slide onto a plate and keep warm, then repeat with the rest of the mixture.