Boil the potatoes in a large pan of boiling water for 15-20 mins until just firm.
Meanwhile, pour the vinegar into a bowl, season and add the herbs, garlic, mustard and oil.
Pour ⅓ of the vinaigrette over the lamb cutlets, reserving the rest for later. Coat thoroughly, cover and leave to marinate while the potatoes are cooking
When the potatoes are cooked, drain and leave until cool enough to handle, then slice evenly and place in a large dish. Pour over the remaining vinaigrette and leave to infuse for 5 mins.
Meanwhile, remove excess marinade from the lamb cutlets, and cook for 2-3 mins on each side under a preheated grill or prepared barbecue. They will be pink at this stage.
Stir the potatoes carefully and serve them warm with the cutlets.
Why not add some finely chopped scallions to your potato salad