Hello fellow stress head.... I unerstand how you feel so I to will not say "don't worry".
I know with DS, I was paranoid about EVERYTHING that went into my mouth. For some reason, this one I have been far less worried about that aspect of things ( bigger things to fuss over).
Remember, even if anything you eat is a listeria risky food, there is still only a VERY, VERY small chance you would actually get it or have it effect your pg. There are loads of mothers out there who don't even think to head the listeria warnings and would continue to eat deli food, soft cheese etc etc. It would still be pretty rare for any of them to have a problem.
Hang in there darl, I'm sure it will be fine. I actually cant see why sour cream/avacado type food would be a problem anyway. The sour cream used (esp in a pub) would usually be the prepacakged, highly processed stuff which is the safest anyway.