Mods (for worsted):
Cast on 24.
2x2 - 14 rounds.
1 round plain, 1 round buttonholes, 1 round plain.
Create upper with M1s on either side of center front 4 for an additional 16 sts.
4 rounds plain. 1 purl round, start decreases. (k2tog at ends on k rounds; p2, p2tog at ends first p round; p1, p2tog at ends second p round)
2 stitch I-cord for ties.