Someday I'll have to try my hand at homemade corned beef and sauerkraut, but for now high-quality deli products work well.
1/2 Tbsp. ketchup
1 Tbsp. mayonnaise
1 Tbsp. sweet pickle relish
swiss cheese, sliced
Mix ketchup, mayonnaise, and relish in a small bowl to make sauce. Set aside. Butter two pieces of rye bread. Heat a skillet over medium heat. Add bread, unbuttered side down. Heat for a minute. Flip bread over and add swiss cheese, a pile of beef and a good helping of sauerkraut. Top with the other piece of bread. Cook for a few minutes. When golden brown, flip the sandwich over. Cook the other side until golden brown. Remove from skillet to a plate. Lift up one piece of bread and spread a tablespoon or so of sauce. Serve immediately.