Boiling the soya chaap is not mandatory but it definitely opens up the layers of the chaap specially when you are not deep drying the chaap.Marination matters: the longer you let your Soya Chaap marinate, the more flavorful it will be. Aim for at least 4-5 hours, or even better if left overnight.No overlapping: To provide even cooking, make sure the chaap pieces don't overlap in the air fryer. If they’re overcrowded, they will not cook evenly.