The store bought ones are mostly bread. I learned the Portuguese sausage trick from a tavern down in Newport. I can't even eat them without sausage now. Steam the clams. Cook the sausage, sweat some minced onions, red pepper and celery if you like. Split the clam shells and chop up the clams. Mix it all together with some fresh chopped parsley, paprika and bread crumbs. Add either the steaming water or clam juice to wet the ingredients. Stuff the shells and bake in the oven until brown. You can toast them under the broiler for a bit if you are feeling fancy. I think the difference between chorizo and chaurico, is that chaurico is smoked.