Using your left needle, pick up the top strand that goes between the needles from fromt to back.
Knit the loop you picked up through the back.
There it is. Work with Work M1R a central stitch to have mirrored increases.
Patterns on my site using this technique: Elizabeth Lise
the slip knot M1L - Make 1 Left Slant M1R - Make 1 Right Slant Mirrored Make 1 Increases 3 needle Bind Off Pompon Tassel