1. In a small bowl mix the 2.5 teaspoons baking powder, 2.5 teaspoons cornstarch, 1 ¼ teaspoons sea salt, 1 teaspoon Kashmiri chili powder , 1 teaspoon garlic powder, and 1 teaspoon sugar to form a dry rub. 
2. Add the dry rub and 2.5 pounds chicken wings to a large bowl and coat and massage the dry rub onto the wings.
3. Line a large baking tray with foil and place a wire rack on top of the lined baking tray. The aluminum foil is helpful later to catch the fat that drips from the wings and save cleanup  but is optional and the wire rack is crucial to help the chicken get air circulation on all sides.
4. Spread the chicken wings on the wire rack and refrigerate uncovered between 4-16 hours. Allowing the chicken to rest with the rub helps remove the excess moisture out the chicken to lead to crispy oven baked wings and allow the spices to season the meat.
5. Preheat the oven to 450 Fahrenheit.
6. Lightly spray the wings with cooking oil before placing them in the middle rack of the oven for 20 minutes. Flip the wings over and cook for another 15-20 minutes until the wings have a golden crispy exterior. 

Make the sauce

1. Prep ingredients for sauce: Finely mince 4 cloves garlic and grate 2 teaspoons ginger root using a microplane.
2. In a small saucepan on medium heat add 3 tablespoons butter and melt. Add mined garlic, grated ginger, and chopped 1 fresno or thai chili to the butter and sautee for ~1 minute until the ginger and garlic softens in order to infuse the butter with the aromatics. If necessary add a tablespoon more butter if there isn't enough fat to coat the saucepan and sizzle the ginger and garlic in.
3. Add 2 tablespoons ketchup, 1 tablespoon soy sauce, 2 teaspoons apple cider vinegar or white vinegar, 2 teaspoons sugar, and ½ teaspoon Kashmiri chili powder to the sauce and mix. Allow the sauce to simmer ~1-2 minutes and turn off the heat. 
4. Coat the wings in the sauce right before serving! Garnish with sliced green onions.