1. Peel celery and onion. Cut celery into thin slices, onion into rings. Sift the flour, add water, add the yolk. To stir thoroughly. 2. Heat vegetable oil in a frying pan. Pour the remaining flour onto a flat plate. Dip vegetables first in flour, then in batter and immediately deep-fry. Place vegetables on paper towels to absorb excess oil. 3. Prepare the sauce. Pour the cream into a saucepan, place over medium heat. Finely grate the Parmesan, add to the heated cream and cook, without bringing to a boil, until the cheese is completely dissolved. Salt, pepper to taste. Pour into a gravy boat and serve with vegetables.