I got a UV one recently as well, my treatment (inspired by Apeks'
instructional video) was a little different than with my non-coated mask, out of an abundance of caution:
- used neutral pH soap, which in my case was liquid dish soap (skin soaps tend not to be neutral, as I've learn with this occasion); all other methods (especially fire) seemed much too risky to me, in terms of stripping the coating
- put a bit on the mask and pushed it around with my finger to cover the inside lens surface
- left it on for a few hours
- rinsed, repeat a few times (did this over the course of a weekend afternoon)
- regular anti-fog treatments before the dive
Hope this helps! Mask has been great so far.