About this opening
Black has taken the pawn, and the first thing to understand is that you are not trying to win it back by force. Qa4 does regain it but wastes time with the queen. e4 is the most played move here. It claims the whole center at once while Black has no pawn there to contest it, and that space is worth far more than the pawn. e3 and Nf3 are the quiet route: prepare Bxc4 calmly and recapture when it suits you. Look at how well White scores across all of these, and note that the quietest move of all scores highest, because Black's difficulty is structural rather than tactical.
Plans
- Play e4 and take the whole center while Black cannot contest it.
- Play e3 and regain the pawn with the bishop at your leisure.
- Do not chase the pawn with the queen, which only loses time.
- Castle short and use the extra space before Black plays c5.
Where the pieces belong
- Pawn: e4, the full center Black has conceded
- Bishop: c4, recapturing the pawn without hurry
- Knight: f3, covering d4 and e5
- Knight: c3, supporting the center
- Rook: d1, on the file the trade opened
You have the center and Black has to free the position with c5 or e5. Stop that break and the extra space does the work for you.