Preheat an outdoor grill or griddle pan to medium-high. In a small saucepan, warm the sauerkraut on the grill or over medium heat. In a medium skillet, bring 1 inch of water to a boil. Add the hot dogs and parboil on the grill or over medium heat to heat through, about 5 minutes.
While the dogs heat through, in a small bowl, combine the sour cream, ketchup and smoked paprika. If using the pickle relish, stir in here.
Split the dogs lengthwise but do not cut all the way through, butterflying them open. Place them cut side down on the grill or griddle and crisp up the casings, 2 to 3 minutes. Cover each dog with a slice of swiss cheese folded to cover the dogs evenly. Cover the grill or griddle with a loose foil tent to melt the cheese.
Set the cheesy dogs into the rolls and top with a slather of sauce and the sauerkraut. If using the pickle spears, place on top of the dogs.