Toss zucchini and 1/2 teaspoon salt in large bowl. Let stand 5 minutes. Transfer to sieve. Press out excess liquid; place zucchini in dry bowl. Mix in egg, yolk, 1/2 cup flour, cheese, and 1/2 teaspoon salt. Mix in parsley, onions, and dill. If batter is very wet, add more flour by spoonfuls.