Mmmmmm Malt Vinegar Beer /sigh

Dog fooding is the best way to describe my feeling now. I'm drinking my 6th batch and my 2nd Lager attempt... An American Light (I was shooting for an Asahi Super Dry clone). Anyway, it had a sulfuric taste when I kegged it. As a Lager that's to be expected so I did the prudent thing and let it sit (and lager) for a few weeks. Now it has developed the treaded malt vinegar taste hinting towards an infection. The Sulfur smell is gone and even though it tastes like something that I should put on my fish-n-chips I'm drinking it and it's actually not terrible.

I've had plenty of successes to be happy about even a molson like lager that turned out great and my wife and I drank that batch in record time

All is not lost yet, the vinegar taste has not gotten worse over the last week so maybe I'm just experiencing green lager beer.

Suspected cause: I used my formerly pristine racking tubes for an airlock/runoff config and it got gunk in it that a starsan soak (for days) and a warm water rinse would not clean out. I used it for racking to my keg with a tiny bit of visible gunk in the tubing and I thought that would be harmless. My Molson Lager was racked with the same tubing and didn't cause any issues. Just in case I will now keep my run-off tubes separate from my racking tubes.

Another reason this is a great hobby: You get to drink your mistakes and piss them away.

first off StarSan is not a cleaner so soaking anything it if for days wont help. you needed to soak it in a cleaner like PBW or Oxyclean for a few hours. how long did you let it lager? typically you want to let it go for 1 week per 10 points of OG. for example say your OG was 1.050 you would let it lager for 5 weeks.

I let it lager for 3 weeks at 1.050 OG

Thanks for the tip about Starsan. Would I have been better off with a bleach solution? (that was what I used to use).

Well, you could always fry up a mess o'fish.
You could just dip the fish right into your beer and when you drink it, it'll taste like the fish too! Kind of a win-win situation
JK, I hope time mellows the batch for you!
Good luck!