Gavin:
Below are some lousy pictures of my aforementioned "brookie flies."
I guess I should name the pattern like all of the other famous and infamous fly anglers/fly tiers out there so let's call it:
"Bamboozle's Boob Brookie Bait." 😎
They are nothing more than a short length (maybe 3/8" -1/4") of 1/8" - 3/16" diameter cylindrical foam lashed to a size 16 or 18 hook in the center. I used to buy the foam from Bill Skilton but sadly he is out of the foam fly material business, however I think Wapsi offers similar stuff.
I wrap a base layer of the same color thread on the hook first, to help stabilize the foam. I always use 3/0 non-bonded thread with foam because smaller sizes of thread can more easily cut through the foam.
I like them in yellow & orange but any color will work. If it makes you feel any better about yourself or the brook trout, tie them in black, brown or olive and convince yourself the fish take them for an insect not a Jujubes or strike indicators... 😉
If you are sober, they take approximately 30 seconds to tie.
Good luck if you tie some and try some!!!