Sunday Chess Puzzle, December 12

Today's chess puzzle is above. I played black. A couple moves ago, I succeeded in weakening the white king's protective pawn structure, leaving the king open to a successful attack. During the game, I tried to attack white's kingside, directly, but I missed a fun tactic on the queenside until a few moves after this position. The problem is that white's pieces on the queenside are rather crowded in by both black and white pawns. How can black take advantage of this to win material in at most 6 moves?