My mom's famous recipe is easily adapted for tuna. To make pareve, substitute mayo for the sour cream.
1 (15 oz) can Salmon, or 2 small cans of tuna
3 eggs, separated (yolks)
¾ cup saltines, crushed (about 13-15)
Mix all ingredients (apart from egg whites) together.
Beat 3 egg whites until very stiff and white, fold into the mixture.
Fry a large spoonful in oil until brown on both sides.