Start a wood campfire and wait until the flames die down and the coals glow red with white ash. Lower a grilling grate so that it sits above the coals and you have nice, even medium heat. Wash the potatoes well in cold water, prick each all over with the tip of a knife and rub them all over with olive oil. Rub salt all over the potatoes; this will help crisp the skin. Tightly wrap each potato in aluminum foil.
Place the potatoes on the grill grate over red coals (medium heat) and cook about 1 hour to 1 hour 15 minutes, turning halfway through. (Feed the fire with more wood as needed.) When done, the tip of a paring knife will go straight through the potato without resistance (you can do this through the foil).
In a small bowl, combine the scallions, chopped herbs and sour cream. Set aside.
Cut the potatoes open through the foil and peel back the foil to expose the potato. Squeeze the potatoes gently from the bottom to expose the soft, fluffy insides. Season with salt and pepper, top with butter and finish with a big spoonful of the herbed sour cream.
Photograph from "Guy on Fire: 130 Recipes for Adventures in Outdoor Cooking"