Good is bad when Best exists

This is one of those kick-yourself-in-the-rear experiences when I missed a clearly winning combination in this position. I had just played my knight to d6 and my opponent pushed his pawn e6-e5, attacking my queen. My continuation was not bad at all, coming out a pawn up in a rook and pawn ending which ultimately was drawn. I could have done better. So, what is White's winning move here? Please, don't go for your computers yet. Try to work it out, and there's plenty of combinations. When ready, look at the Move List for the analysis.