Put the rice flour into a shallow dish and add half the Brussels sprouts. Toss to coat and shake off the excess flour.
Transfer the Brussels sprouts to the pan and immediately cover with a lid for 30 seconds as Brussels sprouts will splatter vigorously. Allow the Brussels sprouts to cook until dark brown and crispy, about 2 minutes. Stir and cook 2 to 4 additional minutes.
Remove with a slotted spoon and transfer to a paper-towel lined plate. Repeat process with remaining 1/4 cup olive oil, Brussels sprouts, and rice flour.
Transfer to a serving platter and serve warm.