Materials:
Requires about one skein for the women's (medium) size.
One set of size 5 US dp needles.
Cast on 40 stitches, dividing them on 3 needles as follows: 10-20-10
Work K1P1 rib for 15 rows. Then, 2 rows stockinette

Begin Heel Flap:
Work across first needle. Turn.
Now, working back and forth only on the stitches on the two needles with fewer stitches (combining them on one needle if you feel more comfortable) and turning the work each row:
P one row (wrong side). Slip 1, knit 1 for one row 16 rows
End with a wrong side row (right side facing you ready to begin).

Turn Heel:
Slip 1, knit 12 (14, 9), slip 1, knit 1, passed slipped stitch over knit stitch, turn.
Slip 1, purl 6, purl 2 together, turn.
Slip 1, knit 6, slip 1, knit 1, psso, turn.
Repeat last two rows until all stitches have been worked--8 stitches left.

Gussets:
Pick up 10 stitches on left side of flap, work across stitches on center needle, pick up 10 stitches on right side of flap. Knit half the heel stitches onto this needle, put the other half onto the needle where you picked up the first group of stitches.

Knit one row around.

Decrease Row:
Row One: Knit to within 3 stitches of end of first needle, slip 1, knit 1, psso, knit 1.
Work center needle.
On third needle, knit 1, knit 2 together, finish row.
Row Two: Knit one row even.
Repeat these two rows until you are back to the number of stitches you cast on (40). (8 rows)

Knit 30 rows stockinette.

Toe:
Decrease Row:
1st needle: Knit until 3 stitches from end, slip 1, knit 1, psso, knit 1.
Needle 2: Knit 1, knit 2 together, knit to 3 stitches from end, slip 1, knit 1, psso, knit 1.
Needle 3: Knit 1, knit 2 together, knit to end
Work one round even.
Repeat until you have 16 stitches left. Place 8 stitches each on just two needles.

Thread yarn onto needle and darn toe together.
Or, use the Kirchener Stitch to close the toe.