Buy grilling chorizo for this and not the cured, slicing chorizo as its too hard in the sauce. The fresh cooking chorizo can be skinned and the meat broken up or chopped so it ends up like mince.
Potato chips, prepared as before
1 onion, peeled, halved and finely chopped
250g cooking chorizo, broken up
400g or 1 can of chopped tomatoes
300ml chicken stock
120-150g grated manchego or another hard cheese
A handful of chopped coriander
Put the onion in a heavy-based saucepan with the chorizo and cook it on a medium heat for 6-7 minutes, stirring as it's cooking so the meat breaks down.
Add the tomatoes and stock, season, and simmer gently with a lid on for about 30 minutes. The sauce should be quite thick – if not, continue simmering until it thickens.
Add the chopped coriander and remove from the heat. Serve the sauce over the chips and scatter the cheese on top.