Yuki's Golden Fork: a fork puzzle

Black to move. Find the one move that wins. About 1100 ELO.

From a real ChessLvl game against Yuki Tanaka (LVL 1). Black to move: one move wins.

Hint

One knight move can attack two pieces at once.

What is a fork?

One piece attacks two or more enemy pieces at once. Your opponent can only save one.

How to spot it

Find two loose or valuable pieces that one of your pieces could reach from the same square. Knights and queens fork best.

Tip

Forks win material because your opponent can only save one piece. Look for two targets one move from the same square.

Solve it on the board above, or take a hint. Every ChessLvl puzzle is checked by a chess engine to have exactly one best move.