Peel and slice the onion finely into shards
Heat the olive oil in your skillet over a low heat
Add the onion and cook for 6-8 minutes, stirring occasionally
Meanwhile, beat the eggs in a medium size bowl
Season the eggs with salt and pepper, remembering that if you are using salted crisps you will not need much salt!
Add the crisps and stir well
Once the onion has softened, add the chorizo and cook for 30 seconds
By now the crisps should be slightly soft and well covered in egg
Tip the egg/crisp mixture into the pan
If you are using a cast iron pan, transfer it to the air fryer or under the grill
Cook in the air fryer at 220C for 5 minutes or so, or under the grill untill the top is set
If you are using a frying pan, cook on one side for 2 minutes or until the egg is firm, then invert the pan onto a plate and slide the omelette back in on the other side to finish cooking
Serve garnished with freshly chopped parsley