Preheat the oven to 4-5, 180°C, 350°F.
Bruise the herbs to release the flavours. Add the rum, sugar and lime.
Place in a shallow dish, add the lamb crowns, cover and leave in the fridge for about an hour (basting occasionally with marinade).
Place into a foil lined roasting tray and scrunch the foil around the mini joints, pour over the juice. Roast in preheated oven for calculated cooking time:
Medium:- 25 minutes per 450g/½kg plus an extra 25 minutes.
Well Done:- 30 minutes per 450g/½kg plus an extra 30 minutes.
Serve with minted rice and roasted leeks.