Soak chickpeas in a large amount of cool water for 24 hours. Rub the soaked chickpeas with your fingers to help loosen and remove skins. Rinse and drain well. Spread chickpeas on a large clean dish towel to dry.
Blend chickpeas, coriander, parsley, onion and garlic in a food processor until a rough paste forms. Transfer mixture to a large bowl. Add gram flour, coriander, cumin, sriracha, salt and pepper; mix well. Cover bowl and let mixture rest for 1 hour.
Preheat an air fryer to 190 C.
Add baking powder and bicarbonate of soda to the chickpea mixture. Mix using your hands until just combined. Form 15 equal-sized balls and press slightly to form patties. Spray falafel patties with cooking spray.
Place 7 falafel patties in the preheated air fryer and cook for 10 minutes. Transfer cooked falafel to a plate and repeat with remaining 8 falafel, cooking for 10 to 12 minutes.
Feel free to try harissa sauce in place of the sriracha.