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

Cover the bowl with plastic wrap and refrigerate the mixture for 30-45 minutes.

Once chilled, remove the mixture from the fridge and roll it into 1 to 1.5-inch balls.

Set up a dredging station with flour, beaten eggs, and panko breadcrumbs.

Coat each ball in flour, dip in beaten eggs, and roll in panko breadcrumbs.

In a deep pot, pour vegetable oil to a depth of about 2 inches and heat to 350°F (175°C).

Fry coated balls for 2-3 minutes until golden brown and crispy.

Transfer fried Reuben Balls to a plate lined with paper towels.

In a bowl, whisk together mayonnaise, ketchup, sweet pickle relish, hot sauce, smoked paprika, Worcestershire sauce, and minced onion or onion powder.

Serve hot, arranged on a platter with the spicy dip.