Start the yellow 70 denier behind the eye and lay a smooth base back to the bend. Yellow thread is chosen deliberately. It glows through the translucent biots and warms the whole body up, so keep the wraps even and don't bury it under bulk.
Tie in a short, sparse bunch of copper-olive Coq de Leon fibres at the bend for a tail about two thirds of a shank long. Sparse is the point on a wet fly: a heavy tail makes the fly track badly on the swing.
Tie in the tannish yellow and rusty spinner turkey biots together at the bend, tips aligned, with the notched edge facing back so the wraps throw a raised rib rather than a smooth one.
Wrap the paired biots forward in touching turns to the 70% mark and tie off. Wrapping them as a pair gives the two-tone banding that separates a sulphur from a PMD depending on which colour catches the light. That ambiguity is exactly why this fly covers both hatches.
Dub a small, slightly built-up thorax of hot yellow Micro Flash to the 85% mark. Keep it short and dense; it exists to give the partridge something to flare against and to put a hot spot right under the hackle.
Tie in a natural partridge feather by the tip, stroke the fibres back, and take only one and a half to two turns before tying off. One turn too many and the fly stops breathing and starts spinning on the swing.
Sweep the hackle rearward, build a tidy thread head, whip finish and set it with a touch of Solarez Bone Dry.