In a large mixing bowl, combine the shredded corned beef, well-drained sauerkraut, Swiss cheese, cream cheese, Dijon mustard, garlic powder, onion powder, salt, and pepper. Mix well.

Cover and refrigerate the filling for 30–45 minutes to firm it up.

Shape the chilled filling into 1 to 1.5-inch balls and place them on a lined baking sheet.

Set up a dredging station with flour, beaten eggs, and panko breadcrumbs in separate shallow dishes.

Roll each ball in flour, then dip in egg, and coat with panko breadcrumbs. Optionally, repeat egg and breadcrumb steps.

Heat vegetable oil in a deep pot to 350°F (175°C).

Fry the balls in batches for 2–3 minutes until golden brown.

Drain excess oil on a paper towel-lined plate.

For the dip, whisk together mayonnaise, ketchup, sweet relish, hot sauce, smoked paprika, Worcestershire sauce, and minced onion until smooth.

Serve the warm Reuben Balls with the spicy Thousand Island dip.