A search for checks for Black turns up Qb1; a search for loose White pieces turns up the bishop on b7. Qb1+ would indeed be a winning queen fork if the pawn on b3 weren’t in the way. So now the position becomes easy: to move a pawn, take something it protects. Black plays RxN; White replies b3xR; and Black then has Qb1+, taking the bishop next move and netting two pieces for a rook. Anytime you have long open lines available to your queen, inspect them carefully for opportunities like this.