Preheat oven to 350 F. (Edit: I now usually bake them at 400 or even 415 F. I find they stay crispier and cook up a bit faster.)
Scrub and slice potatoes. Coat slices well in coconut oil (I find it easiest to do this by putting them in a plastic bowl with a lid, adding the oil, and then shaking them for a minute or two). Add a bit of extra coconut oil to the cookie sheet as well. (Another edit: My preferred method for oiling the fries is now to put frozen chunks of beef tallow, or else a spoonful of coconut oil, on the pan and stick it in the oven while it preheats. The oil melts nicely and the pre-warmed tray helps them cook better)
Spread slices out on oiled cookie sheet. Sprinkle lightly with sea salt.
Bake for 20 minutes, then flip. Bake another 20 minutes and flip again. Then bake for 10-20 minutes until finished, depending how crisp you like them.