The midfielder snapped up from Hertha Berlin last week made his mark in the second half of this competitive friendly encounter against the Blue Square Premier side.
He owed his goal to Andy Barcham as the striker carved Grays open down the right but chose the right option in squaring to Boateng, who made no mistake from close range.
Boateng played in central midfield and was substituted just after his goal after 55 minutes.
That goal restored our lead and the game was put beyond doubt 15 minutes later when Taarabt rifled into the top corner from 20 yards.
We started brightly and took just over five minutes to register as Mills climbed high at the far post to head home from O'Hara's corner.
Barnard and Boateng soon fixed their sights at Knowles' goal and the keeper did well to turn around O'Hara's fierce drive after 13 minutes.
Boateng tried again a few minutes later but as temperatures rose following a couple of un-friendly tackles, the home side edged into the game.
Hearn went close with a free-kick and from an identical position, left of central on the edge of the box, the same player delivered another telling set-piece that led to the equaliser. This time the curling effort flicked off a couple of heads and Forecast, who must have been unsighted, could only parry into the path of Watson who tapped home from six yards.
The remaining few chances of the half fell to Spurs as Huddlestone's goalbound effort was blocked by Haverson and both O'Hara and Taarabt dragged shots just wide.
The second half didn't provide the same goalmouth action as the first with the goals the highlights - Boateng's cool finish as previously described 10 minutes into the half followed by Taarabt's thunderbolt with 67 minutes on the clock.
More chances came as the game opened up, Barcham was inches off target and Knowles saved well as Taarabt unleashed another fierce drive.
However, the last word went with the home side as substitutes Kedwell and O'Connor combined, O'Connor sliding in at the near post to make it 3-2 with a couple of minutes left.
Grays Athletic: Knowles, Sambrook, Stuart (Ashton, 46), Oli, McAllister (O'Connor, 75), Murray, Hearn (Day, 71), Watson (Kedwell, 75), Cooksey (Gross, 64), Marshall, Haverson. Subs: Flitney, Lawson.
Spurs XI: Forecast, Riley, Berchiche, Huddlestone, Ifil, Mills, Routledge (Barcham, 46), Boateng (Maghoma, 57), Barnard, O'Hara, Taarabt. Subs: Butcher, Casey, McKenna, Livermore.
Kevin-Prince Boateng marked his debut with a goal as our Spurs XI team toppled Grays Athletic on Tuesday night.