Julio found another sacrafice with 31....Rxd4 and after 32.Rxd4 Qg1, black picks up the rook on d4 with a nice x-ray attack. Not only does Julio win the rook back, but is also picking off all of white's pawns. White resigned on the following move.
If white were to try playing 31...Rxd4 32.Kxd4, then black wins with 32...Qxf4! 33.Kc3 Qxf3 34.Kd2 Qf2 35. Kc3 (If 35.Kc1 Qc2 mate) 35...Qc2+ 36. Kb4 Qxd1 and black is up a piece for nothing.
A nice geometric tactic from GM Becerra.