Choose potatoes of approximately the same size. Wash very well. Put it in a pot with a thick bottom, or in a frying pan with high edges. Add water. Cover with a lid and put on a high heat. After boiling the water, reduce the heat to a minimum and leave the potatoes under the lid until ready (about 15-20 minutes). Periodically check with a toothpick whether the potatoes are ready.
If the potatoes are ready, but there is still water left, then open the lid, make the fire at maximum and wait until the liquid completely evaporates.