Cut both ends off of the celery root so that it can sit flat. Then using a sharp knife, cut off the outer peel all the way around.
Cut the celery root into slices that are as thin as possible. once you have cut all of the slices, lay each one flat on a cutting board and run your knife over the surface to shave down any of the thicker parts so that it is very thin.
Sandwich Press
Once the sandwich press is warm, place a celery root slice in, close the lid and leave to cook for 3 to 4 minutes until grill marks form and the celery root is tender and pliable. Set aside and repeat with the remaining slices.
Grill Pan
Heat a grill pan to medium high heat. Place a celery root slice onto the pan and place a baking sheet or bowl onto the slice to create some pressure (this will make the tortilla more pliable). After 2 minutes of cooking, flip the slice over and continue cooking for another 2 minutes on the other side. Set aside and repeat with the remaining slices.