Best move I never played

A great puzzle-position from one of my games. Unfortunately, I didn't find the best move until I was analyzing later. Can you find it?

Haven't checked with a program but f3 doesn't quite look right to me. It might very well still be winning, but it seems after 1. f3 exf3 2. e4 fxg2 3. exd5+ Kd7 and black got counterplay he didn't have before with his passed pawns.

I thought the tactic was 1. Rxd5 Kxd5 2. Bc7, which looks winning (2... Ra8 3. Kb6 or 2... Rb1 3. a7 Ra1+ 4. Kb6 or 2... Rb1 3. a7 Kxc5 4. Ka6).

There might be other options - white has a winning position here. Black is almost in zugzwang.

They look scary, but the passed pawns won't make it home. After c6+, the bishop covers f2 and g1. White should promote and win easily.

Just checked with Houdini and he agrees. White has a winning advantage but 1. f3 seals the deal.

Also, my suggested move is wrong. For instance, 1. Rxd5 Kxd5 2. Bc7 Rb2/b1 3. a7 Ra2+ (only move) 4. Kb6 g3! and black queens and wins.

Yes, I only saw it after Critter suggested it as best move by a wide margin. I stared in disbelief for a bit before figuring out what was going on.