Steps

1. Arrange wings in a glass baking dish.
2. Sprinkle evenly with 1/4 cup of salt.
3. Turn them over and springle with the rest of the salt.
4. Chill the wings two hours.
5. Rinse the wings in a colander under cold water and drain.
6. Clean the salt from the baking dish.
7. Arrange the wings in a single layer with the onion slices on top.
8. Mix the yogurt and water together.
9. Pour the yogurt evenly over the onions.
10. Chill, covered, from 12 to 24 hours.
11. Discard onions and drain the wings in the colander.
12. Mix the flour, coarse salt, pepper, and hot pepper in a shallow bowl.
13. Dredge the wings until coated with the flour mixture.
14. Arrange them top side up on wax paper and leave for 15 minutes.
15. Sprinkle the remaining flour mixture over the wings, patting to adhere, and let stand another 15 minutes.
16. Heat the oil and butter over high heat in a heavy skillet.
17. Add the wings, in one layer, top side down, and reduce heat to medium high.
18. Cook wings covered until deep golden, about eight minutes.
19. Turn wings and cook uncovered, until deep golden, about six minutes.
20. Transfer wings with tongs onto a rack, set over the baking pan, to drain.