In the original Star Wars (1977), Darth Vader says to Obi-Wan Kenobi: "I was but a learner, now I am the master" about their last fight that was presumably the one which took place on Mustafar.
In the new ever expanding canon, Obi-Wan and Vader fought in the Obi-Wan Kenobi series and might do in future works.
So my question, and I can presume that the Expanded Universe has ended and is now labeled as Legends, is there any other occurrence where they did fight after that battle?
In Legends, they didn't fight or meet each other between Revenge of the Sith and A New Hope.
It's hard to offer direct evidence for a negative claim like this, but the only time I'm aware of that Obi-Wan leaves Tatooine between Episodes III and IV in Legends is in the first couple of books of the young-reader series The Last of the Jedi (not to be confused with the later film). He doesn't meet Vader in the series.
Also, at least as late as 2007's The Rise and Fall of Darth Vader, it was explicitly stated that on the Death Star, Vader hadn't seen Obi-Wan since their duel on Mustafar:
"I sense something... a presence I've not felt since..." Since Mustafar. Then it hit him. Obi-Wan Kenobi... He's alive!
The Rise and Fall of Darth Vader via Google Books; emphasis added
