There’s only one trick here. It’s all in the onions. You’ll need:
3 red onions, sliced finely
1 chorizo ring, sliced into coins
2 pointed peppers, sliced lengthwise into thin strips
1 large potato, cut into 2cm cubes
8 eggs, beaten gently
1 large knob butter
50g grated parmesan
Salt and pepper
Melt the butter, and put the onions in the frying pan with a large pinch of salt over a medium heat. Now go and do something else, and don’t look at them again for twenty minutes. Give them a stir. Do something else for another twenty minutes; if your house is like mine, something somewhere is crying out for a duster. Stir again, and add the potato cubes. Surf the web for the next twenty minutes (you’ll find some interesting links on the right). Stir again, this time adding the peppers.
Your onions have been sauteeing now for an hour with a little salt, which has driven lots of the liquid out of them. They will have turned soft, brown and caramelised. They will be sweet and buttery. You will have trouble not eating them straight out of the pan; restrain yourself. Better things are on the way.
Continue to saute, stirring now, for five minutes, or until the peppers have become soft. Spread the sliced chorizo evenly over the top of the pepper and onion mixure, and then pour over the beaten eggs, which you’ve grated some pepper into.
Keep the pan on the heat until only the top is wet. Sprinkle over the parmesan, and then put under a medium grill until the egg has set and the cheese is turning brown. Gorgeous red juices will be leaking from the chorizo. Slice and serve with some salad and crusty bread. This tortilla is also absolutely wonderful served cold as part of a picnic.