Heat vegetable oil in a skillet over medium heat for cooking the onions.

Cook chopped onion until soft and translucent, about 4 minutes, then stir in minced garlic for another 30 seconds. Remove from heat.

In a mixing bowl, combine cooked corned beef, cream cheese, Swiss cheese, sauerkraut, parsley, mustard, and onion-garlic mixture. Mix until creamy.

Shape mixture into small 1-inch balls and chill for 30 minutes.

Set up bowls for coating: one with flour, one with egg whites, and one with crumbs. Roll each ball in flour, dip in egg whites, and coat with crumbs.

Fry the balls in hot oil until golden brown, about 3 minutes per side. Drain on a wire rack.

Serve warm with Thousand Island dressing.