The visitors had flown into a first-half lead, when Daniel James slotted a low drive past Cameron Byrne-Hughes to open the scoring.
But an inspired United turnaround in the final twenty minutes turned the game on its head as first James Scanlon converted from close range.
Our young Reds completed the comeback when Jim Thwaites thumped home an 81st-minute penalty, after an impressive solo display.
And there was still time for Scanlon to add a third in injury time, as he grabbed his second goal of the evening, to put the game beyond Boro altogether.
FIRST HALF
It took the visitors just twelve minutes to find the opener at Carrington, with Lucas Harrison spreading a superb pass into the feet of James.