Heat a large, wide saucepan over medium-high heat, about 3 minutes. Add half the oil and brush to coat.
Add half of the bok choy, cut sides down. Cook 3-4 minutes, until browned. Remove to a plate and repeat with the remaining oil and bok choy.
Meanwhile, whisk together the sauce ingredients, except for the konjac flour.
Return the bok choy to the pan. Pour in the sauce. Bring to a boil. Reduce heat to medium-low, cover, and cook about 10 minutes, until bok choy is just tender.
Remove the bok choy to a serving platter. Mix the konjac flour with 2 tablesooons cold water, and stir the mixture into the saucepan. Bring to a boil. Cook, stirring, until the liquids turn into a thick sauce, 3-5 minutes. Spoon the sauce over the bok choy and serve.