This mouthwatering pork tenderloin is stuffed with chorizo, cheese and spinach. Once you master stuffing a pork tenderloin--you just cut the tenderloin almost in half lengthwise, pound it, fill it and tie it closed with kitchen string--you won't want it any other way. Serve with sautéed red peppers tossed with capers, parsley and sherry vinegar and roasted potatoes. To double this recipe, use 2 skillets or brown the tenderloins one at a time.