Combine soup and 1/4 cup water. Add 1 cup chow mein noodles, the tuna, celery, cashews, onion; toss lightly. Place in ungreased 10 x 6 x 1 1/2 inch baking dish. Sprinkle remaining noodles over top. Bake at 375 degrees for 15 minutes or until heated through. Garnish with mandarin orange sections. Serves 4-5.
To double recipe, bake in 11 1/2 x 7 1/2 x 1 1/2 inch baking dish, 25 minutes or until hot.