Step 1: Prepare the Filling
Drain the sauerkraut thoroughly in a colander, then place it on paper towels and squeeze out as much liquid as possible—this step is critical for preventing soggy egg rolls. In a medium bowl, combine the chopped corned beef, shredded Swiss cheese, well-drained sauerkraut, and ¼ cup Thousand Island dressing. Mix until everything is evenly distributed.

Step 2: Set Up Your Assembly Station
Place your egg roll wrappers on a clean, dry work surface. Keep them covered with a slightly damp towel to prevent drying out. Have your beaten egg and a pastry brush ready in a small bowl. Position a wrapper in front of you in a diamond shape (one corner pointing toward you).

Step 3: Fill the Egg Rolls
Place about ⅓ cup of the Reuben filling in the center of each wrapper, slightly below the center point. Don’t overfill—you need room to fold and seal. Brush all four edges of the wrapper lightly with beaten egg.

Step 4: Roll and Seal
Fold the bottom corner up over the filling, tucking it slightly under the filling to create a tight roll. Fold in the left and right corners toward the center, then continue rolling tightly away from you until you reach the top corner. Press the edges firmly to seal. The egg wash will act as glue. Repeat with remaining wrappers and filling.

Step 5: Frying Method
Heat about 2-3 inches of vegetable oil in a large, heavy-bottomed skillet or Dutch oven to 350°F (use a thermometer for accuracy). Carefully place 2-3 egg rolls at a time into the hot oil, being careful not to overcrowd. Fry for 3-4 minutes, turning occasionally, until golden brown and crispy on all sides. Remove with a slotted spoon and drain on a wire rack or paper towels.

Step 5: Baking Method (Alternative)
Preheat your oven to 425°F. Place assembled egg rolls on a baking sheet lined with parchment paper. Spray all sides generously with cooking spray or brush with oil. Bake for 18-22 minutes, flipping halfway through, until golden brown and crispy.

Step 6: Serve
Let the egg rolls cool for 2-3 minutes (the filling will be very hot). Arrange on a serving platter, garnish with fresh parsley if desired, and serve immediately with Thousand Island dressing for dipping.