Herringbone half double crochet
A US hdc variation passes the new loop through the first hook loop before finishing.
Counted practice swatch
Chain 17. Begin in third chain for 15 stitches; ch2 does not count in this version.
Work the repeat
Yarn over, insert, pull up a loop and draw that new loop through the first loop on the hook. Yarn over and draw through the remaining two loops. Ch2 to turn, repeat in every stitch.
Read the fabric
That first slip-through gives the slant. Keep it separate from an ordinary three-loop hdc finish and retain 15 top Vs across each row.