Preheat XL air fryer to 390F.* (See Notes for Stovetop Cooking)
Russian Dressing – To a medium bowl, add all ingredients, and whisk to combine. Taste, and make any necessary flavor adjustments; set aside momentarily. If you’re using store bought Thousand Island, Ken’s Steakhouse brand or Kraft are both good and readily available.
Evenly drizzle or brush one side of each of the 8 slices of bread with olive oil or melted butter.
Place two of the slices, greased sides down, in the air fryer.
Spread a layer of Russian dressing over the tops, as desired.
Add 1 or 2 slices of cheese to each piece of bread. Note – Based on the size of both the cheese and the bread, and how cheesy you want your sandwiches, you may only use 1 slice per slice of bread, but I use two.
Generously mound the corned beef on each piece. Note – You’ve got 1 pound of meat and the recipe makes 4 sandwiches total, so evenly divide the meat into 4 portions.
Top the corned beef with horseradish, as desired.
Optionally, drizzle each with additional Russian dressing or Thousand Island, as desired. Note – You may not use all of the Russian dressing you mixed up but better to have a little extra than not quite enough.
Top each with a slice of bread, greased sides up, and press lightly to “seal” the sandwiches.
Close the air fryer basket and fry for 8 minutes total, stopping to check and flip at the 4 minute mark. Tips – Based on your exact model of air fryer, how thick your sandwiches are, etc. cooking time will vary so start checking for doneness a couple minutes early. Although don’t be afraid to cook longer than 8 minutes total if your sandwiches aren’t looking done at that point.
Remove the two sandwiches from the air fryer.
Repeat steps 2 through 12 to make two more sandwiches.
Slice and serve. Reubens are best warm and fresh although will keep airtight in the fridge for up to 3 days.