Day of the Dove
The Day of the Dove (HD Video; Memory Alpha) starts with Kirk getting punched in the face by a Klingon, and quickly goes downhill from there.
Best part
The Klingon Captain Kang is played by the Technomage from B5.
Worst part
Basically everything else in the episode. There’s some terrible sword fighting, Klingons in blackface, a being that’s crazy powerful but stupidly scared, a total lack of backstory, a simple plot mechanic with no twist, and a sixties pean to race relations that’s so guileless it doesn’t even pretend to be anything else.
Grade
D