Preheat oven to 375 degrees. In saute pan, saute the onions in 1 tablespoon oil until lightly tanned. Add sauerkraut (watch out for splashing) and cook for 8 minutes more until dried. Using a plate as a template, cut tortillas to even rounds with paring knife. Lightly coat bottoms of 3 tortillas with vegetable oil and lay out on cutting board. Spread with 1/2 of the cheese. coat with single layer of corned beef, then sauerkraut. Cover with another single layer of corned beef, then with remaining cheese and tortillas. Press down to compact. Lightly coat tops with vegetable oil. Bake for 10 minutes until lightly browned on the outside and melted on the inside. Cut each quesadilla into 8 wedges. Serve with Russian Dressing.
Mix all ingredients together well, and chill until needed.