The thickness of tortilla or frittatas presents a challenge to the cook, because it necessitates a long cooking time, which can produce eggs with the consistency of Styrofoam. If, like me, you don't fancy tipping the half-cooked tortilla on to a plate and returning it to the pan the other way up, you may have to set the top under the fierce heat of the grill, further increasing the risk of toughening the eggs.
An alternative is to use the oven. It worked pretty well for me.
Serves 3 to 4.
6 medium-sized new potatoes
1 large, Spanish onion, sliced
Large knob of butter
80g hard cheese, such as Manchego or Pecorino (but the cheese on the omelette above is Cheddar), grated
Scrape the potatoes, cut them into slices roughly the thickness of 2 £1 coins, put them in a saucepan of lightly salted water, bring to a simmer, and cook until tender. Drain.
In a heavy pan - the one above is 20cms, and has, as you can see, a detachable handle - and in a tbsp or two of oil, gently fry the onions, lightly salted, until golden. It will take 10 to 20 minutes.
Lightly beat the eggs with a fork. Lift the onions from the pan with a slotted spoon, and stir them into the eggs, along with the potatoes. Add a little more salt, if you like.
Over a low heat, melt the butter in the pan. Tip in the egg mixture. My inauthentic addition - a regular theme of this blog - is the grated cheese on top.
Put the pan into a gas mark 4/180C oven for about 20 minutes, or until the egg is set.