Dà Fǎn cuō 反撮 "Pinch Opposite"
Use the thumb and the middle finger to pluck two strings in an opening motion, away from the palm. The plucked strings must have four strings between them. If using own nails, only the nails touch the strings.
Kao suggests that Chaozhou teachers may call this Fēi zhǐ 飞指 “Flying Finger”. Ferguson also offers the term Pēn zhǐ 喷指 “Puff Finger”.