Add the chorizo to a cast iron pan and cook on medium heat until browned. If your sausage is in a casing, snip it open with kitchen scissors and squeeze out the meat. When browned, remove from the pan and set aside.
Wash and slice the potatoes thinly, ideally on a mandolin (no need to peel them). Place one layer of potatoes at the bottom of the pan and season with salt. Spread about a third of the refried beans over the potatoes, sprinkle on a third of the browned sausage, a third of the chopped herbs and top with a third of the cheese. Repeat twice more, finishing with a layer of potatoes, cheese and herbs.
Bake for one hour or until the potatoes are tender and the cheese is melted.