Marinated in spiced yoghurt, Kashmiri chillies, and garlic, then roasted over roaring tandoor charcoal embers with charred edges.
Lightly crush the mustard and fennel seeds coarsely.
Whisk the yogurt with the crushed seeds, nigella, turmeric, chili powder, mustard oil and salt; coat the chicken and rest 3 hours.
Thread the chicken pieces onto skewers.
Grill over high heat, basting with mustard oil, until charred at the edges.
Serve hot, finished with a squeeze of lemon and sliced onions.