Lay a thread base, then bind a strip of red open-cell foam along the shank as an underbody, the soft foam compresses so it adds shape without bulk, and clip the end off at the rear so a small red egg sac projects behind the bend.
Tie one strand of Mirage opal flash in pointing off the back, fold the other end back and tie it in too, then cut the loop so you are left with two short flash strands trailing behind as bubbles.
Tie in the yellow-dyed grizzly hackle at the rear. Barb length does not matter here because it gets trimmed short later.
Dub a very slender pale yellow Super Fine body forward to the 50% point of the shank, taking one wrap of dubbing behind the hackle so the hackle cannot slide off the back of the body.
Palmer the hackle forward over the body in three or four turns, tie it off and clip the tip, then rotate the fly and trim every barb very short so the rib is just a band of fuzz.
Tie in a small bunch of Mirage flash as an underwing, binding it down over the front half of the shank, and trim it off level with the egg sac.
Clip a small chunk of white snowshoe hare hair from the bottom of the foot, pull out the longest fibres and even it up by hand, no stacking, then measure it slightly longer than the underwing, trim it to length before tying in, and secure it on top with a soft loop pulled tight.
Tie a short post of the same red foam in on top for visibility, then dub a little more Super Fine over all the tie-down wraps to cover the thread and give the hackle a platform to bite into.
Tie in the light barred ginger hackle at the back of that shoulder and palmer it tightly forward to the head; tie off and trim the tip.
Brush all the hackle back, clean up the head with thread so nothing crowds the eye, and whip finish.
Turn the fly over and trim a V out of the hackle underneath so the body sits down in the surface film.