Finely chop the corned beef and drain the sauerkraut well.

In a large bowl, mix the chopped corned beef, sauerkraut, mashed potatoes, and Swiss cheese until combined.

Form the mixture into golf ball-sized orbs and chill on a lined baking tray for 30 minutes.

Prepare a dredging station with separate bowls for flour, beaten eggs, and breadcrumbs.

Roll each ball in flour, dip into the egg, and coat with breadcrumbs.

Heat oil in a deep fryer or heavy pot to 350°F (175°C). Fry the balls in batches for 3-4 minutes until golden brown.

Drain fried Reuben Balls on a wire rack or paper towels.

In a separate bowl, whisk together mayonnaise, ketchup, relish, hot sauce, paprika, and garlic powder for the dipping sauce.

Serve hot with the spicy Thousand Island dipping sauce.