Authentic good food in Saint Petersburg

Hi there:

Just booked a trip to Saint Petersburg for December this year and already read the previous postings (like the suggestion to eat in big hotels... yaik :( ).

I will definitely hit the "Art of Russia" place run by Eka http://progoblin.ru/test/places.html

However, I was wondering if somebody else might have any suggestions as to where I can find AUTHENTIC and DELICIOUS Russian food that is not extremely expensive and in rather "normal/laid back" locations.

Thanks a lot in advance...

Chow, chow :)

Stefan