This little fly has a cult status with many Czech fly fishermen. It consists of only the simplest materials possible - a hook, a bead, hare dubbing, and ribbing of some kind; the tail is entirely optional - but in the hands of a skilled nymph fisherman it has wondrous potential. I have friends who fish this fly (and only this fly) for the whole season with excellent results.
Now with fly fishermen being fly fishermen there are many who just know that their interpretation of the Little Tart is better than others - some swear by gold head, others by dull nickel, and I have witnessed serious bar room fights about what is the "correct" part of the hare's pelt for the dubbing. Or about as serious as bar room fights between fly fishermen ever get...
#12 heavy gauge hook (Skalka Lake for me)
3.5mm caliber tungsten bead (dull nickel for me)
rooster hackle fiber tail (not essential, but I like it)
gold tinsel ribbing
hare dubbing (the best is from the back of an old male hare)