Peel the potatoes and cut off the round ends so you have a flat edge at either side, then cut in half. Rinse under cold water and pat dry.
Place oil into pan over high heat. Place potatoes in pan and fry until golden brown, about 5 minutes on each side.
Turn heat down to medium, add the butter, rosemary, thyme and garlic to the pan (use the flat side of your knife to press down on the garlic to crack it open). Fry for about a minute, then add the liquid stock and water. Season with salt and black pepper, cover and cook for 15 to 20 minutes (or until potatoes are soft), adding a little water as and when required.
Remove from heat, place potatoes in a serving dish and pour over any remainder of the gravy from the pan. Garnish with fresh thyme sprigs and a sprinkle of sea salt flakes.