Spurs, who won 4-0 at Aston Villa on Boxing Day, were forced to come from behind at the Stadium of Light after John O'Shea had put Sunderland ahead in the 40th minute.
An own goal from Carlos Cuellar and Aaron Lennon's fine strike - in the space of three second-half minutes shortly after the restart - secured the three points.
"It was an excellent performance," said Villas-Boas. "It is very, very difficult to do what we have done and we have to congratulate the players because they have been absolutely amazing.
"These are extraordinary wins for us. So hopefully if we can keep the momentum in January it will be excellent.
"We made the game a little bit more difficult. In the first half we dominated and had the best chances but went 1-0 down from a set-play.
"If you don't come back quickly into the game, the game drags on and it is difficult for you to recover a result. But we came very strong mentally in the second half and I think we got what we deserved."