Marinated in spiced yoghurt, Kashmiri chillies, and garlic, then roasted over roaring tandoor charcoal embers with charred edges.
Toss the fish cubes with lemon juice and salt and rest 10 minutes.
Whisk the yogurt with roasted gram flour, ginger-garlic paste, ajwain, Kashmiri chili powder, and 1 tbsp mustard oil; coat the fish and rest 30 minutes.
Thread the fish cubes onto skewers, leaving small gaps between pieces.
Grill over high heat, basting with the remaining oil, for 8-10 minutes until just cooked through.
Char the edges briefly over the flame and serve with onion rings and green chutney.