Working with just 1 flatbread at a time, lay it horizontally on your work surface.
On the long side closest to you, add on 3 slices of Swiss cheese, side by side.
Add 1/3 cup of drained sauerkraut on top of the cheese followed by 2 Tbsp of Thousand Island dressing.
Next add on 1/3 of the corned beef.
Roll it up tightly and cut it in half.
Repeat two more times with the remaining ingredients.
Heat a skillet over medium heat and add in the avocado oil.
Sear the Reubens on all sides until golden brown.