Spin deer hair in tight clumps from the bend to the 75% mark. Use bigger clumps than feel right, and pack each one back hard before spinning the next. Density decides everything here.
Remove the fly from the vise for trimming. Cut the bottom flat and close first. The hook gap must stay clear. Then trim the top and sides into a tent shape: peaked ridge along the top, flaring wider toward the bend, like a moth's folded wings.
Remount. Tie in two stripped brown hackle stems angling forward as antennae.
Wrap 1-2 brown hackles in the front quarter.
Whip finish.
Substitutions
Body/Wing instead of Natural deer hair: Bleached elk hair — Lighter color, same spinning technique; Caribou — Slightly finer, spins well
Hackle instead of Brown: Grizzly — Adds barring, different look; Ginger — Lighter color for evening caddis
Other versions
2 more in the app: Fly Fish Food Tie, variant 1, Fly Fish Food Tie, variant 2.