Marinated in spiced yoghurt, Kashmiri chillies, and garlic, then roasted over roaring tandoor charcoal embers with charred edges.
Coat the chicken in yogurt, ginger-garlic paste, Kashmiri chili powder, garam masala, half the chaat masala, lemon juice, and salt; rest 2 hours.
Thread the cubes onto skewers, leaving small gaps.
Cook over a hot charcoal grill or grill pan, turning, until charred at the edges and cooked through.
Brush with melted butter during the final minutes.
Slide off the skewers, dust with the remaining chaat masala, and serve with onion rings and green chutney.