In a bowl combine the mayo, onions, ketchup, hot sauce, Worcestershire sauce, paprika and salt. Stir until smooth. Refrigerate until ready to use. Makes about 3/4 cup.
Heat a cast iron grill pan over medium to medium-high heat.
Butter two sides of the rye and slather a few spoonfuls of the Russian dressing on the inside of one slice. Next, layer the corned beef, pickles, black pepper, Swiss cheese and remaining slice of buttered rye.
Place the sandwich onto hot grill pan and cook for 3 to 4 minutes or until grill marks appear and the cheese has melted.