Knotted Buttonhole Stitch, as found in Marion Nichols' Encyclopedia of Embroidery Stitches, is the stitch for week 39. Check out Sharon's website, Pintangle for instructions, and don't forget to look at the links of other TAST participants amongst the comments.
Actually I have seen this stitch in two other books: A-Z of Embroidery Stitches 2, where it is called Blanket Stitch - German Knotted, and is worked towards you.
Also in Basic Stitch (Kiso no Stitch) by Sadako Totsuka, Buttonhole Stitch, Variation C. In this Japanese publication the stitch should be worked from right to left, and upside down!
I have found that if I can't 'get on with' a particular stitch it might be because I don't like the instructions in one particular book. Looking in other books, and I might discover an easier way.
However, in this week's case, Sharon's instructions were perfect for me.
Now, what design should I make?
Finally I settled for a circle and worked on curves inside it. To add some sparkle I placed a shisha mirror in the centre and some beads and sequins.
It has finally got a bit coolish and autumnal so I used a piece of brown batik for the foundation. I like batik for my embroidery. The marbled, freckled design adds interest without competing with the stitches.