4 chorizos (the uncooked kind)
1 clove garlic, chopped
1 large red onion, sliced
1 large red pepper, deseeded, cut into fork-size pieces
Chorizos, unlike ordinary sausages when cut up, do not have a tendency to stick to the pan. You may not get a sauce flavoured with crusty bits, but you do get the paprika-spiked oil that the sausages release.
How you cut them up is a matter of taste. You may like discs; I prefer to skin them, and chop them into small pieces.
Put a splash of oil into a heavy pan over a gentle heat. Throw in the chopped chorizos, and fry them gently until they lose their raw colour and throw off their oil. You may find that you now have plenty of oil with which to cook the garlic, onion, and pepper, which you add to the pan now, with a little salt. Stir everything, and cover the pan, cooking the contents gently until the onions and peppers are soft. If they exude a lot of liquid, evaporate it by uncovering the pan while you cook the pasta.
I like conchiglie (shells), or tortiglioni (big tubes, larger than penne), with this.
Of course, numerous variations are possible. You might, for example, add cumin (1tsp), throwing it into the pan and frying it for a minute before adding the vegetables. You might heat up the sauce with dried chillis, or with a tsp of harissa, stirred in once the onions and peppers have started to collapse.