Mount hook, tie in a short-fibered grizzly hackle and olive floss at the bend.
Wrap a slender floss body to the 65% mark, then palmer the grizzly through it in 4-5 turns. The body hackle should be short. Fibers about one hook gap.
Tie in a small bunch of wood duck flank as an underwing, tent-style over the body.
Tie in matched mallard quill slips over that as the overwing, tips to the bend.
Wrap 2 turns of brown hackle at the collar.
Neat head, whip finish.
Substitutions
Body instead of Olive floss: Olive dubbing — Easier than floss, floats better; Olive thread wraps — Slimmest profile
Underwing instead of Wood duck flank: Lemon wood duck (dyed mallard) — Easier to find than real wood duck; Gadwall flank — Similar barring, widely available
Overwing instead of Mallard quill: Mottled Thin Skin — Much more durable; Turkey quill — Different mottling, same shape