Place the potatoes in a large saucepan of cold water and bring to the boil over high heat. Reduce heat to medium and simmer for 12-15 minutes or until just tender. Drain and set aside to cool.
Meanwhile, combine yoghurt, coriander, cumin, garlic, lemon juice, honey and tahini in a small bowl.
Cut the potatoes in half (or if large, in quarters) and place in a serving bowl. Add the dressing and mint and half the shallots and toss gently until combined. Season with salt and pepper. Break up prosciutto and place on top with remaining shallots.