Devised by Clarence Roberts for the golden drake and golden stonefly hatches (although he called it a caddis). Tied here with the spent paired wings in the horizontal, I've seen them at the 3/4 position, too; sidearm is much easier on the rotator cuff (see Dan Quisenberry).

hook - TMC 5212 #8
thread/rib - UTC 70 hopper yellow
tail - pheasant tail
egg sac/body - Congo Hair yellow
body hackle - brown (undersize by 2)
wing - grizzly hackle tips (paired/spent)
front hackle - brown

Part 1

mash barb, start thread at 2/3 mark, wrap back to point above barb

measure (hook length+) some pheasant tail fibers; tie in, smooth butts, return to 2/3 mark

tie in a hank of CH (original calls for wool yarn - sheep don't swim and the first thing Norwegian fishermen do if they fall overboard is peel off those heavy sweaters, hence the Congo Hair), wrap back to tail

create a loop over the pheasant, tie down, then wrap yarn body

tie in hackle, then move thread back to point above barb