Cut the potatoes into small cubes and place in a microwave-safe bowl. Add the stock and water until the potato cubes are covered with water. Cook the whole thing in the microwave at approx. 550 watts for 5-8 minutes (depending on the amount). Possibly place a small plate underneath in case some water overflows. Stir a few times in between.
Mash some of the cooked potatoes a little with a fork. Add vinegar and oil, season the dressing with the spices and possibly add a little more water if the mixture becomes too thick.
Cover and leave to cool in the refrigerator. B. Mix with lamb`s lettuce.