Pekinese Stitch / Chinese Stitch / Forbidden Stitch / Blind stitch is a border or outline stitch where thread is whipped through a base of back stitches.
Make a line of back stitches (tutorial here). Make the stitches nice and even so that the pekinese stitches are the same size.
Bring the needle up slightly below and to the side of the back stitch row. Now skip the first stitch and pass the needle under the second stitch.
When pulling the needle, make sure the lacing / whipping thread is not yanked.
Now turn the needle down and pass it under the first stitch like shown in the picture below.
Note how the needle passes under the back stitch and over the yellow thread.
Next lace through the third back stitch. The needle is pointing up here.
Next pass the needle downward through the second stitch. Again the needle passes under the back stitch and over the yellow thread.
Also note how this stitch is placed neatly to the side of the previous stitch. They are side by side and not intertwined or placed one on top of the other.
Tips for making Pekinese stitch
This stitch will look beautiful only if the back stitches are the same size.
Make sure the back stitch is not too tight and not too loose.
This stitch looks pretty when the pekinese stitch coils are the same size too. Pull them just enough so that the coil is as loose / as tight as the previous one.