¼cupraw, fermented sauerkrautPlace in a small strainer and squeeze the juice out with the back of a spoon. Raw, fermented sauerkraut is rich in probiotic bacteria; you can find it in the chiller section of most supermarkets.
Preheat a tabletop grill, panini toaster, or skillet (medium heat).
Meanwhile, place the tortilla on a clean cutting board. Spread evenly with mustard & mayo and mix the two together with the back of a spoon.
Place a slice of Swiss cheese on one half of the tortilla. Top this with the turkey slices and the sauerkraut you squeezed dry (see description in ingredients). Finally, place the second slice of cheese on top of the sauerkraut.
Fold the empty half of the tortilla over the stacked ingredients. Spray or brush the panini press/tabletop grill/skillet with olive oil.
Place the folded tortilla into the press/grill/skillet and cook until the cheese is melted and the outside of the tortilla is golden-brown and crispy. If using a skillet, press the tortilla down with a spatula, flip after 1½ to 2 minutes, and cook on the other side until golden brown on both sides.
While the tortilla is cooking, toss 2 cups of green leaves (I love arugula), shredded cabbage, or some other crunchy vegetable with olive oil dressing, scatter, if desired, with nuts, cranberries, grated cheese, or cubed apples (as here), and serve onto a plate.
As soon as the quesadilla is ready, place it on a wooden cutting board to cool for a minute. With a large chef knife, cut into three triangles. Serve next to the salad and enjoy immediately, while it's hot and crispy.