In a blender or food processor, blitz all the ingredients together, except for the sunflower oil.
Remove half the marinade, cover and refrigerate (this will be served as a salsa with the rack). Add the sunflower oil to the remaining marinade. Choose a container that will hold the lamb tightly, pour in the marinade and coat the lamb well. Cover and refrigerate overnight ideally or at least for several hours.
Preheat oven to 200C/400F/Gas 6. Heat a griddle pan/barbeque (or frying pan). Remove the meat from the marinade and shake of excess (discard this portion of marinade).
Place the meat on the hot griddle and sear well on all sides, about 5 minutes in total.
Transfer to a baking tray and cook in the oven for about 15 minutes, depending on size of rack and how well you want them cooked.
Slice the rack into chops and serve with reserved marinade.