Place the chicken gizzards, celery, onion, bay leaves and 1 teaspoon of celery salt into a saucepan. Pour in enough water to cover the gizzards by 2.5cm. Bring the gizzards to the boil, reduce heat to low, cover and simmer until tender, about 2 1/2 hours. Pour in more water during simmering, if needed, to keep gizzards covered. Remove the gizzards to a bowl, discard the celery and onion and reserve the stock.
Season the gizzards with 1/2 teaspoon of celery salt, the seasoned salt, pepper, Italian seasoning, garlic granules, cumin and hot pepper sauce, stirring to combine well. Pour 75ml of the reserved stock over the seasoned gizzards and refrigerate for 30 minutes or more, stirring often. (Save or freeze the remaining stock for another use, if desired.)
Heat oil in a deep fat fryer or large saucepan to 190 degrees C.
Place the flour in a plastic bag and pour in the gizzards with their seasoning. Shake the bag to thoroughly coat the gizzards with flour. Gently lower about 1/4 of the gizzards per batch into the hot oil and fry until golden brown, about 5 minutes per batch. Drain the gizzards on kitchen towels and serve hot.
Chicken gizzards may be special ordered at your local butchers.