A chorizo sandwich, as sold in every bar and corner shop across Spain, is nothing more than chorizo slices, sandwiched between bread. The quality of the chorizo and the bread, and the generosity of the perpetrator are the only factors that change.
So it´s not a very good sandwich, really. One dimensional, at best. Inedible, at worst.
Unless you take a little bit of care, and then it is pretty darn tasty.
You need a baguette, a ciabatta or a small loaf of good bread.
You need some proper ibérico chorizo, sliced thin. And it has to be eating chorizo, not cooking chorizo.
Then, taking inspiration from the Majorcan way with sobrasada, you need hot mango sauce, or, failing that, apricot jam mixed with chili sauce.
Heat the oven to 180ºC. Spread the cut baguette with the sauce, layer a fair amount of chorizo slices (be generous. think about your arteries some other day). Close it, wrap it in foil, squash it a little and put it in the oven.
Take it out when the outside is very crunchy, 15 or 20minues. The orange fat will have oozed from the sausage, mingled with the hot, sweet sauce, and soaked the bread.
So far, so heavenly.
But to take it up a notch, serve alongside "ensalada de matanza". This means "pig-killing salad" and is a Spanish slaw, served in Escolástica´s village at matanza time.
Slice some cabbage as thin as you can, and dress very simply with olive oil, salt, Sherry vinegar, a dash of powdered cumin and crushed raw garlic. Not too much of any.
This will provide crunch and freshness, and make the chorizo sandwich into a balanced meal. Or almost.