Trim the bok choy, then cut into quarters vertically. Let drain.
In a large skillet with a cover, heat the oil til shimmery. Add the turmeric and salt and stir a minute. Add a few drops of liquid, stir til turmeric and salt become smooth and un-lumpy enough to add more liquid. Pack in the bok choy, cut sides down. Cover with water and bring to a slow boil. Cover and let cook for about 15 minutes, checking occasionally to make sure the slow boil is being maintained, also to press the bok choy into the liquid to submerge if needed. If the bok choy isn't fully submerged, turn over after 15 minutes. Cook another 15 minutes. Remove bok choy from liquid and serve.