Preheat the oven to 250°F.
Remove the tips from your wings and divide them into flats and drumettes and transfer them to a large bowl. Reserve the tips for stock. Add the baking powder to the wings and toss until evenly coated. Set aside.
In a small bowl, whisk to combine the chili powder, sugar, salt, cumin, oregano, onion powder, cayenne and ground coriander. Pour the mixture over the wings and toss until evenly coated.
Place the dressed wings on a drying rack placed on top of a baking sheet lined with tin foil. Put the wings, rack and all, in the oven and cook for 20 minutes. Increase the heat to 425°F and bake for 30 minutes more.
Remove the wings from the oven and let cool for 5 minutes before transferring to a platter. Keep warm until ready to serve.