I assumed that it would be something like “(ich erzähle) eine Geschichte über das mal, in dem ich...“ but that doesn’t seem right.

And the more I look up how to translate this idea, the more it seems that German doesn’t really even use a translation of the expression „the time that I...“

Would there be a way to say this sentence : „have I told you about the time that I ...(insert story here)“ ? What would be the closest translation?