Repeat until you have 18 holes (36 rounds). Start the instep, knit flat: On 19 stitches, do k1 yo, finishing with k1. Turn and purl back. Repeat k2tog yo netting until 12 holes. Start the sole: Pick up 12 stitches from the side, knit around, pick up 12 more stitches. Decrease with k2tog on either side of the toe every other round until you have decreased four times. Now narrow for heel while continuing to narrow the toe: k2tog on …
Repeat until you have 18 holes (36 rounds). Start the instep, knit flat: On 19 stitches, do k1 yo, finishing with k1. Turn and purl back. Repeat k2tog yo netting until 12 holes. Start the sole: Pick up 12 stitches from the side, knit around, pick up 12 more stitches. Decrease with k2tog on either side of the toe every other round until you have decreased four times. Now narrow for heel while continuing to narrow the toe: k2tog on beginning of 1st needle and end of 3rd needle. Continue until 2 stitches remain on the toe and weave sole together.
The instructions get incredibly sketchy for the instep and sole. The original actually just calls for k1 yo, not k2tog yo, but then the instep would get really huge really fast. It also seems to imply that the sole is knit flat, but that doesn't make a whole lot of sense to me.
Shown with a cast-on count of 45 stitches.