How did I strip the patina off my wok?
I am pretty sure the acidic sauce reduction attacked the seasoning. Short cooking time of acidic elements does not have much effect, but longer cooking times are usually harsh for the seasoning.
It's not a real problem though. It will come back easily. Just continue cooking as usual.
To avoid this, usually Chinese cooking adds the sauce at the end, and uses some starch instead of reducing in stir-fry dishes.

On a side note, I think that your "patina" looks more like burned oil/whatever than seasoning, but it may be because of the quality of the picture. Is it smooth ?