2 Part Technique - After vaulting over your opponent's guard into the mount, an easy solution for when he captures your ankle is the Leg Over Pass. Simply, dismount by swinging your free leg over his chest and landing with a good farside underhook. If he continues to bite down on your foot, utilize Underhook & Head Control vs Half Guard to kick yourself free and secure the pass. If you miss the underhook after the Leg Over, quickly spin about your trapt leg and search for the underhook again, but this time from the Back Step position. Kick your leg free to pass his half guard, and finish on top with solid Underhook & Head Control. If you miss this second chance to pummel the underhook after the spin, heavily wrap your arm over his elbow, making sure to not let him go deeper with his own underhook, and stomp off his half guard to the North South.