This Fork Is Really Good

This player resigned because of this fork where he could've just played Be7 (I think)!

It's the knight on e7 by the way

I think they were lazy with their evaluation.

at first it looks like you're losing a queen

but then you see black can take with bishop

but then you see that if black takes, then white can take e5 with knight, then black takes with rook, then white takes with queen
and thennn it looks like your rook is hanging, but if black takes then white has Bc4+! winning the queen

nice position

actually they weren't lazy. i wrote that line before i even fully evaluated the position. i think they thought you would crush them

actually black would probably take your rook once you move your knight

If white is smart they don't recapture with the rook, they take the rook on h8... White isn't compelled to avenge the knight on e5.   

Black can still win i think

Even after blundering the knight on e7 you were still in a strong position, but you're right, your opponent shouldn't have resigned. They could've turned that around.