Fish this fly on low water in summer for sea-run Trout and Salmon.
As I am not sure of the original pattern for this fly and I learned
it with orange hackle and I have seen it fished well with black
hackle so try a few of each.
Materials for The Green One or Viherpuna:

Hook: Mustad BL 80525 size 10, may not be legal everywhere,
adapt to your conditions.
Thread: Red Benecchi 12/0.
Tag: Oval gold tinsel.
Body: Red Firestar dubbing and Olive Ice Dub.
Hackle: Ring neck pheasant rump feather dyed orange or black.
Cheeks: Jungle Cock (optional).
Head: Tying thread and varnish.
Tying Instructions The Green One or Viherpuna:

1. Set your hook secure in the vice and start the thread
down the hook shank to about between hook point and barb
and tie in the gold tinsel on the underside of the hook.

2. Wrap tinsel 4-5 turns and make a "figure of eight"
and come up between the hook shanks and tie off.

3. Make a little ball with red Firestar dubbing.

4. Dub a front body with Olive ice dub and taper it forward,
making it thicker as you go toward the hook eye, stop a few
mm short of the eye.

5. Now take your Velcro brush and abuse the dubbed body
to fluff it up and give it a little volume.

6. The body looks like this after brushing it out.

7. Pick out a pheasant feather that has most of it´s fibers
intact, I hold it by the tip and gently pull the fibers at
right angles from the stem. I cut off the very tip where you
see the arrow and then tie in the little triangle on the
underside of the hook. (This is shown on the
Simon-fly.)

8. Wind the hackle in tight turns as you hold the fibers
backwards to double the hackle, make sure not to twist the
hackle and keep the stem facing forward at all times.

9. Tie off the hackle and pick out two Jungle Cock feathers
and tie them in. On a fly this size I like them to extend
the green part of the body, maybe a tad more. Trim the waste
and finish off leaving about 1mm of hook shank behind the eye.
I leave that mm space just because I need the room when I knot
on my tippet.
I make the knot so the tippet goes straight through the eye
and becomes an extension of the hook shank so the fly doesn't
slide to its side and fishes at an angle so to say.

10. Find a slow part of your favorite steam, tie it on your
leader and hope one of the big shiny and silvery fishes
fancy your fly. ~ Peder Lindström
About Peder:
I live in a small town called Holmsund just outside Umeå, Sweden.
Holmsund is located on a penisula where Ume-river runs out
in the Bay of Botnia so I am not short on water to fish for
Trout, Grayling, Sea-Trout, Salmon, Perch, Pike and various
other species.
I work for Armstrong World Industries at the Holmsund plant
and have been with the company for 18 years, I am a
machine-operator and safety-rep, member of the plant safety group.
In my spare time when I can find it, I go fishing of course.
That is between taking care of the family and work.
As far as flytying is concerned it is a hobby I picked up
again from my teen years and I have been flyfishing for a
few years only, and everyday I wonder why I didn´t start sooner.
I am also lucky to live where I actually do as far as fishing
goes, from my home and for a 100 miles (160km) north or south
there are 10 Salmon and Sea-trout bearing rivers and streams,
my home water is Ume-river.
Enjoy the flies everone.
Stay safe and take care. ~ Peder