|Black to move|
The last move of white was 1.Ne8. Can I take it? What worries me is the rook on d7. Its defender(s) can be harassed. Can I exchange this problem piece off with 1. ... Rxd1 first? But what about the zwischenzug 2.Nf6+ ? The knight sits well defended on f6.
After I found the solution, I spent ten minutes about thinking why this position takes me so much time, and how I could fix that. I came up with the following reasoning:
1. ... Rxd1 captures a rook. This places the obligation on whites shoulders to take a rook back. White can postpone his obligation with the threat 2.Nf6+ as a zwischenzug. This would work if black had to remove his king. But if black can get rid of the threat by capturing the attacker, and he can, by playing 2. ... Rxf6, he would solve his problem and now he has placed two obligations on the shoulders of white, who must take two pieces back. Since white can only fulfil one obligation in one move, he looses a piece. This idea is always profitable, even when you use two rooks as attackers, and the targets are two minor pieces. In which case black would win two minor pieces for a rook.
This simple rule, in case a capture is met by a threat in stead of a recapture, is usable in a whole lot of situations. It makes those situations much less complicated to judge, without the need to calculate every single line. Finding this rule is the best well spent ten minutes in a long time!
We need to find the flaws in our chess education and fix them. It is better to study 500 positions in depth, than 200k+ positions without learning anything from them. I'm sure there are 4-5 more of these easy fixes waiting for me out there!