French Tarrasch, Korchnoi Gambit
This Tarrasch variation is really nice, and I was recently very lucky to get a draw against a fantastic chess player using what I had researched about this variation.
I'll do my best to share a glimpse into it here, but to really master it would require some research.
I believe it can be a solid repertoire against the French Defense.
Another interesting variation; trying to trap the Queen if the Queen takes the b2 pawn: