But once Canterbury got into their rhythm - in particular their excellent set piece - and once Mo'unga got his hands on the ball, Tasman were up against it, although they re-took the lead through a Hunt penalty, an advantage that was shortlived.
As they tend to do in these parts, Canterbury scored on the stroke of halftime through Tim Bateman and it was a lead they wouldn't relinquish.
It is Canterbury's third successive final victory and their ninth in 10 years, a remarkable run of success.
The match-up between the neighbours - and Crusaders partners - always promised to be close, with Tasman having real talent in their 8, 9, 10 axis through Jordan Taufua, Finlay Christie and Hunt. Fullback Will Jordan is also a player of real ability.
But Canterbury's own key axis of Luke Whitelock, Mitchell Drummond and Mo'unga had far the better of their opponents and the red and blacks have a fullback of talent too in George Bridge.
Like Super Rugby champions the Crusaders on AMI Stadium, Canterbury are extremely hard to beat here and their forward dominance was perfectly displayed halfway through the second half when they put together an extraordinary 34 phases before Bridges was held up over the line. A penalty advantage meant that man Mo'unga put the Cantabs further ahead anyway.
His counterpart Hunt's final act was to kick the ball out on the full. While it was a sad way for departing wing James Lowe to end his time with Tasman, he and his side deserve credit for what they brought to another gripping final.
"For me having a week off and not being able to be the with the boys - I was gutted," Mo'unga said afterwards of missing last weekend's semifinal. "To be back with the team I love - you could see how close we are on the field."
Canterbury 35 (Richie Mo'unga 2, Tim Bateman, Jack Stratton tries; Mo'unga 3 cons; 3 pens)
Tasman 13 (Levi Aumua try; Mitchell Hunt con, 2 pens)
Halftime: 19-13