Start the tying thread behind the eye and wrap a smooth base back to the bend. Select a CDC feather that looks like this one. You want a feather with some length to it, and a bit of taper to the length of the fibers as well. Hans calls this a Type 1 CDC Feather, although this nomenclature has been slow to catch on over here. At any rate, look for a feather that looks like this one.
Separate the fibers on the tip of the feather a bit and tie the tip of the feather to the hook with a loose turn of thread. You want some of the fibers beyond the tie in point to be loose so they will form the "collar" at the front of the fly.
Pull the tip of the feather down to clump the ends into a bunch along the top of the shank. Leave the tips extending to the front end of the hook to help form an underbody for the fly.
Wrap forward over the tip of the feather forming a smooth thread base up to the index point.
Grab the butt end of the feather in a pair of hackle fibers and proceed to wrap the feather forward up the hook shank. these first few turns will result in a body that looks much like dubbing to start with.
As you reach the front half to one third of the body area, the loose fibers on the CDC feather will come into play. Continue wrapping the feather as you were, allowing the loose fibers to splay around the hook like a soft hackle. It may help to fold the fibers back with your fingers as you wrap to clear the way for the next turn.
Continue wrapping the loose portion of the CDC feather forward, forming a ragged collar of flowing CDC fibers.
When you reach the index point with the CDC feather, fold any loose fibers back along the body and tie the tip of the feather off with a couple firm wraps of thread.
Clip the butt end of the CDC feather flush and build a smooth thread base over the butt end as well as the bare portion of the index point.
Cut, clean a stack a bundle of deer hair. You want hair with nice clean steeply tapered tips with some diameter to the hair immediately below the tips. The amount of hair you use is up to you and how you intend to fish the fly. Dress it sparsely for flat water and a bit more heavily for rougher water. Measure this clump of hair so it extends from just behind the eye of the hook back to the bend.
Clip the hair to the length you just measured, and lay it along the top of the shank with the butt ends just behind the eye of the hook. It is easiest to grasp the hair in your material hand and then clip the butt ends to length so the hair is in the correct hand once it is trimmed, as passing the short bunch of hair from hand to hand can be tricky. Place two turns of thread over the hair, about an eye length from the butt ends. Make sure these wraps lay one on top of the other.
Hold the hair in place while you tighten the two thread turns by steadily pulling the bobbin toward you. The butt ends of the hair should flare into a nice little semi-circle.
Make two turns forward through the butt ends of the hair to bring it right up behind the eye. These two turns are made at about a 45 degree angle to the shank and work to further lock the hair into place.
With the thread right behind the hook eye, whip finish in front of the butt ends of the hair. Clip the thread.
CDC & Elk
Hook: TMC 100SP-BL #12-20
Thread: 8/0 or GSP 50 Brown
Body/Hackle: Tan or Natural Dun CDC
Wing: Deer Hair