In a large mixing bowl, combine finely chopped corned beef, diced Swiss cheese, well-drained sauerkraut, cream cheese, Dijon mustard, garlic powder, onion powder, and black pepper. Mix until all ingredients are fully integrated and creamy.

Cover the bowl with plastic wrap and refrigerate for at least 30 minutes.

Once chilled, use your hands to form the mixture into 1 to 1.5-inch balls and place them on a lined tray.

While the balls are chilling, prepare your breading station with bowls of flour, beaten eggs, and panko breadcrumbs.

Heat vegetable oil in a deep pot over medium-high heat until it reaches 350°F (175°C).

Carefully add the shaped balls in batches to the hot oil, frying for 2-3 minutes until golden brown.

While frying, prepare the Spicy Thousand Island dipping sauce by whisking together mayonnaise, ketchup, sweet relish, hot sauce, and paprika.