Caro Kann Counter Gurgundize Attack
This off beat variation to me looks somewhat dodgy for Black to play due to the major structural weaknesses created by playing B5. However, as a surprise weopon against the ill-prepared then you probably will be ok, but my general results against it have been good. So why B5? Well the key to this system is actually B4. If you do not play A3 then the pawn will land there and be a slight thorn in the side. In fact, if it does I have found hitting it head on with C3 or A3 is not bad (not immediately) and then you can go after the weaknesses in the black queenside.
So, no deep analysis required and I think A3 for white is probably best. Looking at my database, this has scored well for white. If however the gamble works and white does not play a3 then black has a good attack on whites queenside.