The striker who bagged a treble against Barcelona in the NextGen Series a month ago did it again as the lads completed the first half of the season in style.
Coulthirst opened the scoring in the fourth minute from Roman Michael-Percil's cross before Michael-Percil scored from 12 yards via an assist from Grant Ward midway through the first half.
The lads continued to dominate in the second half and were eventually rewarded with Coulthirst's second goal for 3-0 in the 83rd minute after more good work from Ward.
His hat-trick goal wasn't far behind as Kenny McvEvoy's shot was parried Coulthirst was on the spot to bury the reound.
It was the team's final fixture in National Group Two of the newly-formed Barclays U18 Premier League and a third-place finish means they will line-up in Group One for the second half of the campaign.
"The first half was probably the best 45 minutes we've played this season, we played really, really well," said Academy Manager, John McDermott.
"It was always going to be difficult to maintain that in the second half against a hard-working Sunderland side, but we managed to score another two goals and that was pleasing.
"Shaq has always been able to score goals, but his work off the ball is improving. He's very conscientious, a diligent trainer and it's through hard work and application that he continues scoring, not just down to luck.
"Special mentions to Connor Ogilvie, who was excellent at centre-back and Grant Ward at left-back, probably his best performance so far this season."
Spurs U18s: McGee, A McQueen, Ball, Ogilvie, Ward, Dombaxe, Bentaleb, Onomah, Michael-Percil, McEvoy (Miller, 88), Coulthirst. Unused subs: Priestley, Gardiner, Lesniak, Winks.