Toast cumin, coriander, cloves, and peppercorns in a dry pan for 2 minutes.
Grind toasted spices with fenugreek, turmeric, paprika, chilli, cinnamon, and salt into a powder.
Mix the spice powder with garlic, ginger, and yogurt in a bowl.
Cut duck breasts into bite-sized pieces and stir into the yogurt marinade.
Cover and refrigerate the duck for at least four hours or overnight.
Thread duck pieces onto metal skewers leaving 1 cm to 2 cm between chunks.
Grill skewers on the highest heat for 3 minutes near the heat source.
Turn skewers and grill for another 3 minutes until charred and cooked through.
Slide duck off skewers and serve with onion, coriander, and lime.