The Blues returned to winning ways after two successive defeats to sail through to the last 16 of the Capital One Cup - and the Chilean was delighted their rampant display.
He declared: “We played well - especially in the first half. Maybe in the second half, winning 4-0, we stopped our pace a little bit but I am pleased because we started this game after two disappointing defeats in the Champions League and Premier League.
“It was important to continue in this cup and it was important to try to win from the first minute. We scored four beautiful goals.”
Pellegrini fielded a strong side against the Black Cats but named five youngsters on the bench - three of which were introduced in the second half.
The boss asserted it was necessary to start with experience to create a comfortable platform before blooding the starlets in a competition he wants success in once again.
He continued: “We won this cup two years ago and it is beautiful to play the final at Wembley. We will continue to try and play strong squads in this competition.
“We have a lot of players injured so it was not easy to play this game.
“It was important to start with a strong team and then to give minutes to young players during the game.
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The 62-year-old also reserved praise for his new recruits, particularly Kevin De Bruyne and Raheem Sterling.
“Kevin is a very good player and Raheem played very well also,” he said. “He scored two goals and it was useful for both players to be settled in our team.
“It is not easy at the beginning to make the correct movements but both of them demonstrated why they are here.”
Sergio Aguero also wrote his name onto the scoresheet with a penalty, although the Argentine ace could - and perhaps should - have added to his personal tally, when he spurned a fantastic opportunity to make it 5-0 after rounding the goalkeeper with the goal at his mercy.
Despite that miss, Pellegrini was pleased with Kun’s performance, reflecting: “These things happen.
“Maybe he thought the player couldn’t cover the goal but he scored the penalty and he was involved in the other three goals.”
When asked about the likelihood skipper Vincent Kompany could return to action against Spurs at White Hart Lane this weekend, he replied: “We will see from now to Saturday which players can recover.
“We have a lot of injured players - at least eight. I hope we can recover at least some of them.”
