Do You Know How To Analyse? Part 2

Kotov recommends we analyse the following position where Black's moves are largely forced before proceeding to read about the analysis of unforced variations, and so I began this task during my lunch break today.

Boleslavsky vs. Ravinsky, 1949 (variation)
Kotov position #9
Black to move

The question is "... what variations would arise after 20. ... Ke8 21. Nd6+ Kf8 22. Qf3+ Nf6 23. Re1?"

As my copy of 'Think Like A Grandmaster' is conveniently printed in two column format, I folded the page in half so as to hide the solution and spent twenty minutes or so looking at the diagram. This should be around the time required to complete the whole excercise - I got as far as 'clearly ennumerating the candidate moves'. Not too great a concern, I'll be happy to get the method and technique correct before working on speed... "It is better to do something once slowly and correctly than ten times quickly and wrong".

Static Assessment: Black is a Rook for a pawn ahead in material, in compensation for which White attacks Black's insecure King. There's an absolute pin on the Knight at f6 which is also attacked by a pawn. White has a discovered check by moving his Knight at d6. Difficult for Black to close lines to his King or hide it in the corner, while White potentially has a weak back rank.

Candidate Moves: In listing the candidate moves, I also decided to make a brief note about the underlying idea befind each.

A. 23. ... Bc5 - defending the discovered check.
B. 23. ... Qg4 - to exchange material, Black threatens to win by attrition.
C. 23. ... Bxe5 - to relieve pressure on the pinned Knight, clearance of the d-file aiming the major pieces at White's weak back rank.
D. 23. ... Kg8 - unpinning the Knight.

Here's the position from which the analysis really starts, although it should be done from the position given above.

After 23. Re1