With just one ingredient (beside the hook and thread) the impressionistic LGF (Little green f**ker) is the easiest fly in the world to tie.
Hook: TMC 200R, weight optional
Thread: 8/0 olive or brown
Tail, body and thorax: 1 maribou plume (shade of olive or light green)
Wrap a thread base (and optional lead wire weight.) Pick a maribou plume and stroke fibers towards tip. Strip off fibers that don't reach the tip and trim stem. Tie in maribou tips as a tail (hook shank long) then wrap thread forward to behind eye.Twist remaining maribou into a loose rope and wrap forward. With maribou held straight up behind the eye, tie off with 2 or 3 turns of thread. Pull maribou back towards tail, build a small head behind the eye and whip finish. Trim remaining maribou at a 45º angle down and back towards tail. Use a loop knot when fishing so the big head imparts a free, wriggling motion to the fly when stripped.