sounds like you did a potts fracture... 10 months later... I'd be getting you to run on it, but wouldn't expect it to be super painful. It doesn't sound like your medical management was adequate - e.g. no post cast xray to confirm healed and no physio to guide your rehabilitation.

You need to get an xray to check if it's still damaged and need to see a physio to help guide your rehab... specifically - ROM exercises to ensure the ankle is fully mobile post fracture, the physio can also mobilise the joint to help with this. you need strengthening exercises especially of the everters as they are the muscles in the area of the break and they will have become very weak. And most important because your a sports person your need proprioreceptive exercises to help you prevent getting further injury - this is mostly wobble board and standing on 1 leg.
However before you go doing much exercise a repeat xray is worthwhile to really check you won't damage it further by going into a heavy snowboard season. at 10 months though any healing that was supposed to take place should be done by now. so best to just get a very good physio who can guide you through the new season