Large baking potatoes
butter
Kosher salt
table salt

Thoroughly wash potatoes.  While wet, coat each with kosher salt.  Wrap each tightly in foil.
Start charcoal according to directions.  Coals should be completely white.  Place potatoes around (not in) coals.  Cook for 1 ½ hour flipping every half hour.  Remove from coals and carefully un-wrap.  Split in center and add butter and salt to taste.