Place chicken gizzards, celery, onion, bay leaves, and 1 teaspoon celery salt into a saucepan, and pour in enough water to cover the gizzards by 1 inch. Bring gizzards to a 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.
Once cooked, remove gizzards to a bowl, discard celery and onion, and reserve the broth.
Season gizzards with 1/2 teaspoon celery salt, seasoned salt, pepper, Italian seasoning, garlic powder, cumin, and hot sauce, stirring to combine well.
Pour 1/3 cup of the reserved broth over the seasoned gizzards, and refrigerate for 30 minutes or more, stirring often. (Save or freeze the remaining broth for another use, if desired.)
Heat oil in a deep-fryer or large saucepan to 375 degrees F (190 degrees C).
Place flour in a plastic bag, and transfer the gizzards with their seasoning into the bag as well. Shake the bag to thoroughly coat the gizzards with flour.
Gently lower the gizzards into the hot oil in batches, and fry until golden brown, about 5 minutes per batch. Drain the gizzards on paper towels, and serve hot.