Place a 30cm shallow casserole pan on a high heat, strip in the rosemary leaves, add 1 tablespoon of olive oil, and crisp up for 1 minute while you dice the lamb into 3cm chunks.
Scoop out the rosemary and put aside, adding the lamb to the pan for 2 minutes to get some colour.
Meanwhile, squash the olives and remove the stones.
Drain the pickled onions and stir into the pan with the olives.
Toss well, then pour in the tinned tomatoes, breaking them up with a wooden spoon, as well as 2 tins’ worth of water.
Cover and cook in the oven for 2 hours, or until thick, delicious and tender, stirring halfway and loosening with a splash of water, if needed.
Taste, season to perfection with sea salt and black pepper, sprinkle over the crispy rosemary leaves, and serve.
