DS9 s3e19 “Through the Looking Glass”
It's a Mirror episode, and you know what that means! Andy's gonna like it and Matt's gonna hate it - OR will our opinions be mirror-universed too?? Sisko steps into the Mirror Universe and boy, is he sorta shrugsville about it. And his dead wife Jennifer is back! Oh man, can't wait to see how Sisko's gonna...huh, just sort of chill about it. But at least Bashir/Vantika is back! Which is basically Mirror Alliance Bashir. [Episode discussion begins around 1:01]