Thoroughly scrub each of the potatoes and place them into a large saucepan full of water over a high heat.
When the water comes to a boil, stir in the salt. Place a lid on the pan, reduce the heat to medium-high and leave the potatoes to boil for 20-25 minutes. Check on the potatoes every 5 minutes and stir.
When you think the potatoes are cooked, carefully prick one with the tip of a knife to make sure. If it's full cooked, there will be no resistance.
Drain the water from the pan and turn off the heat. Return the pan to the hob and leave the potatoes to dry. When the skins are shrivelled and the potatoes are grey and covered in salt crystals, they're ready.