Cook the potatoes in boiling salted water for 10 to 15 minutes, or until tender, then drain. Meanwhile, squeeze the seeds from the tomatoes, and destone the olives.
Heat a lug of oil in a large frying pan over a high heat, add the lamb rack and sear until golden, then remove to a plate.
Crush the drained potatoes and tip into the frying pan, then fry for a couple of minutes over a medium-low heat.
Stir in the tomatoes and olives, then season with sea salt and black pepper. Pick in the rosemary, scatter over the unpeeled garlic cloves, and drizzle with a little oil. Transfer to a roasting tray.
Place the lamb on top of the potatoes. Depending on the size of the racks, the lamb will take somewhere between 20 and 30 minutes to cook, but will still be pink in the middle – use your instincts (add 5 to 10 minutes if you like your meat well done).
When the lamb is cooked to your liking, slice it into chops and serve with the crispy potatoes. Delicious served with a little salsa verde or an extra drizzle of oil.