To make the sauce, place cottage cheese, French dressing, 1/2 teaspoon of lemon juice and the salt in a blender, and blend on high speed until creamy. Transfer the sauce to a small bowl, and stir in the pickle relish. Cover and chill until ready to serve.
Place the tuna, bread crumbs, and egg whites in a large mixing bowl, and stir to mix, breaking up any large pieces of the tuna.
Add the celery, onion, parsley, and lemon juice to the tuna mixture, adding onion salt to taste. Mix thoroughly.
Place the cereal in a large resealable plastic bag, and close the bag. Cover with a kitchen towel, and use a rolling pin to crush the flakes into fine crumbs. Transfer the crumbs to a shallow dish, and set aside.
Using your hands, firmly pat the tuna mixture into eight cakes of equal size. Press the cakes into the cereal crumbs, covering all sides.
Lightly coat a large baking sheet with cooking spray, and arrange the cakes on the sheet. Lightly spray the tops of the cakes with the spray, and bake in a preheated 350°F oven for 25 minutes, or until lightly browned, turning once during baking.
Serve hot, topped with a spoonful of the chilled sauce and garnished with fresh parsley.