Put the cutlets in a shallow dish. Finely grate half of the ginger and combine with the garlic, turmeric, chilli flakes, and vinegar. Pour the spiced vinegar over the lamb making sure it is well coated. Cover with plastic wrap and leave in the fridge for 4-6 hours, or overnight if you have the time.
For the crust: shred the remaining ginger. Heat the butter in