Dress the hook with the 14/0 thread, making every wrap count — the whole point of this fly is to keep it sparse.
Tail: three or four Coq de Leon fibers, a little shorter than the shank, tied on top. Unwrap the thread flat as you bind them so they lie smooth and don't roll around the shank.
Tie in X-Small copper Ultra Wire and bind it in going back, unwinding the thread a little more so the tie-in is covered neat and flat.
Rib the fly with a couple of counter wraps, stopping about two-thirds of the way up the shank, and capture the wire off there.
Wing: catch a small piece of white electronics shipping foam in by a point, wrap back a short way, then trim it short and round off the corners. The double wing is what gives the fly its buoyancy and keeps it emerging.
Blend a 50/50 mix of UV Callibaetis Ice Dub and blue dun rabbit dubbing, spin a thin noodle on the thread and build a dubbing ball, leaving a little space toward the eye for the hackle.
Pick a Hungarian partridge feather from the neck or head of the bird, where the fiber length is right, and grasp the very tip with fine tweezers to keep the tie-in point small. Tie it in by the tip and fold it back.
Make a small thread base and take one to three turns of partridge — keep it really sparse, which is what lets all the fibers move in the water.
Whip finish, trim the thread, then find the main stem of the hackle feather and clip it out without cutting anything else.