Tartakower Caro-Kann

(I am going to presume you mean Bg6 else your post makes no sense)

Basically in this variation your give your opponent a strategic plus (center, better pawn structure) and as compensation you get dynamic play. You have to make use of your dynamic play or else it will go away while the strategic plus is structural and is here to stay.

The main idea dynamic idea of the Tartakower variation is that the added pawn on your kingside gives additional safety for your king.

The standard plan therefor (especially if white castles short) is to:

1. Finish development

2. Use your extra pawn or even multiple pawns to create a weakness on the enemy king side (your king should remain rather safe due to the extra pawn)

3. Use the weaknesses to create counter play to compensate for the white strategic plus

Taking this in mind you can understand why taking back with the f-pawn is worse than taking with the h-pawn. Taking with the f-pawn leaves you with a weaker king once you start advancing your king side pawns to creates weaknesses in the enemy camp thus making it a lot harder to advance these pawns. In other words your are removing dynamic potential from your position (making you worse) if you take back with your f-pawn

So the idea is to take back with the h-pawn (keeping maximum safety for your king) and than find a break to the enemy king-side pawns. Probably something with .. g5 and then ... f5. Your king is still save while the opponents king side will be blown up giving you dynamic counter play.

Hope this helps