1. Preheat the oven to 428°F (200c fan oven).
2. Begin by peeling and crushing the garlic. Make the marinade by mixing together the coconut cream, lemon juice, chilli, garlic, olive oil, salt and cumin seeds (it helps if the oat cream has been chilled first as it thickens up and acts as more of a yoghurt marinade).
3. Lay the boned leg flat, fat side down to begin with. Trim the meat so that it becomes level, scoring and cutting the joint if necessary, so that you end up with a flat piece of meat, reasonably even in thickness. Layer the marinade over both sides of the meat, working it into all the corners and cuts -use all of the marinade and pile it on thickly.
4. Lay the meat on to a rack in a large roasting tin. Cook for 30 -- 35 minutes, this will produce slightly pink meat in the centre, so cook for longer if you like it well done. The spiced cream will make a fragrant crust which may scorch, but do not worry as this only adds to the flavour. Once cooked, remove from the oven cover loosely in foil and allow to rest for 15 minutes. When ready, slice in to thick wedges and serve.