Mount the curved hook and lay a smooth yellow thread underbody all the way to the bend. The yellow glows softly through the biot once it is wet. That warm underbody is part of the pattern.
Tie in a biot at the bend by its tip and wrap it forward to about the 65% point, forming a clean, segmented body. Any biot color you have on hand works; match it to the natural you are imitating.
Tie in a natural tan CDC feather over the thorax as an emerging wing. A low loop/puff that sits in the film. Lucian Vasies uses hand-selected Troutline CDC here.
Spin a pinch of guard hair from a hare's mask into a dubbing loop, then wrap it as a short, spiky hackle collar at the thorax. The guard hairs give the fly legs and a lifelike water print without adding bulk.
Whip finish a small head. The finished fly should sit half in, half out of the surface film. Body hanging below, CDC and hare hackle riding in the meniscus.