In a small bowl, mix together mayonnaise, grated onion, ketchup, sweet pickle relish, paprika, and salt. Set aside.
Assemble the Sandwiches:
Butter one side of each slice of bread.
On the unbuttered side, layer: a slice of Swiss cheese, a generous portion of corned beef, sauerkraut, a dollop of Thousand Island dressing, and another slice of Swiss cheese. Top with the second slice of bread, buttered side up.
Cook the Sandwiches:
Heat a skillet or griddle over medium heat.
Place sandwiches in the pan and cook for 3–4 minutes per side, pressing gently with a spatula, until the bread is golden brown and the cheese is melted.
Serve:
Slice the sandwiches in half and serve immediately with pickles or chips on the side.
Serving and Storage Tips
