The German manager had lost his first four games in charge of the Tynecastle team but they looked more resolute throughout the contest.
His side were in control after Ryotaro Meshino's opening goal, but a red card for Sean Clare and the resulting free-kick from Niall McGinn lets the Dons back into the game.
The Jam Tarts started poorly in their Boxing Day derby defeat and could have seen the same fate had Bruce Anderson not missed an early chance, shortly before Main had an effort blocked.
They did look more organised than on Thursday, as they began to take possession and saw Meshino fire a shot wide.
The Japanese attacker came closer to scoring 10 minutes later, seeing his rolled effort cleared off the line by a last-gasp Scott McKenna block. He and Lewis Ferguson shortly received bookings for a scuffle. Aberdeen sunk further and further on the back foot, unable to escape their own half.
Craig Halkett, captaining Hearts in place of the dropped Christophe Berra, also tested Joe Lewis from close range towards the end of the first half. It was another chance in what looked like a reinvigorated Jambos performance.
Meshino looked the most likely to create magic in the first half and he went a step further shortly into the second. His 25-yard effort found the top corner and Stendel finally had a Tynecastle goal to celebrate.
Dons top scorer Sam Cosgrove was serving the last of his two-game suspension and his absence was telling, with the away side missing a focal point in attack.
Things had been in Hearts favour until a quick Aberdeen free-kick put Anderson through on goal. Pulled back by Clare, the midfielder was shown a straight red.
It was a double whammy as McGinn, who came on for the injured Zak Vyner, placed the resulting free-kick into Joel Pereira's goal with perfection. In the space of a minute Hearts' lead, and momentum, was gone.
He could have put Aberdeen in front minutes later, had his cut-back from Anderson been placed with more precision.