Mix all the marinade ingredients together in a bowl.
Butterfly your leg of lamb and cut so it is a pretty similar thickness all over. Don't worry if it had gnarly bits, these will form a crunch.
Place the lamb and the marinade into a ziplock bag and massage the marinade into the meat.
Put into the fridge overnight.
Setup your Egg for a direct cook at 200°C with the stainless grid.
Cook the lamb for about 15-20 minutes on each side. You're looking for some caramelisation.
Take your lamb off the Egg when the internal temp is about 5°C below where you want it to be.
I like my lamb medium-rare (57°C) so I take the lamb off when it is 52°C. Some parts may have gone beyond this, they'll still be lovely.
Rest your lamb in foil after cooking for at least 15 minutes.
Serve sliced.