The North Yorkshire club confirmed that they had recaptured Sunderland winger Jack Diamond shortly before Tuesday evening's match got underway, beating off competition from a host of other interested parties to land the highly-rated 21-year-old on loan for a second time.
Orsi, a summer signing from Maidenhead United of the National League, then demonstrated his goal-scoring prowess with a trio of clinical finishes to extend his new side's unbeaten start to the campaign into a fifth match.
The 25-year-old opened his Harrogate account just before the interval when Stags goalkeeper George Shelvey failed to hold Alex Pattison's strike from the edge of the box and he pounced on the loose ball, spun and fired home.
Jordan Bowery spurned a golden chance to level matters seven minutes into the second period, smashing a penalty against the cross-bar, and Mansfield were made to pay just seconds later.
Harrogate broke countered immediately, Lloyd Kerry’s pass setting Simon Power clear down the left, from where the Irishman crossed for Orsi to take a touch and make it 2-0.
George Lapslie did get the visitors back in the contest on 66 minutes, netting with a powerful effort which Joe Cracknell found too hot too handle, though the hosts' two-goal lead was restored within a couple of minutes.
And it was that man Orsi who did the damage once again, tapping in from almost on the goal line after strike partner Aaron Martin's header was parried by Shelvey.
Meanwhile, Town have confirmed that fans' favourite Diamond, who scored in the club's National League play-off final victory over Notts County back in August 2020, has been handed the number 21 shirt and will remain at Wetherby Road until the end of the season.
Harrogate Town: Cracknell; Fallowfield, Smith, Hall (Burrell 64), Sheron; Thomson (Muldoon 78), Pattison (Falkingham 77), Kerry, Power; Orsi, Martin. Unused substitutes: Oxley, Page, McArdle, Armstrong.
Mansfield Town: Shelvey, Clarke, Rawson (Oates 54), Ward, Burke; Charsley, Hill, Lapslie (Caine 68), Law; Bowery, Sinclair (Cooper 77). Unused substitutes: Bishop, Gordon, Clarke, Johnson.
Referee: A Haines (Tyne & Wear).