Put the chestnuts into a bowl with sea salt and water. Soak for 15 minutes. When ready, rinse well.
Place the chestnut flat-side down. Cut the bulge side widthwise with a sharp knife. Slice a straight line or score an x.
Finally, add the slitted chestnuts into a pot or deep pan along with a quarter cup of sugar, a tablespoon of olive oil, and enough water to where they are almost submerged. Cover the pot with a lid and cook on medium heat for 15 minutes. When you remove the lid, they should all have opened and are ready to eat.