The winger started in a two-man strike-force and netted Spurs' second of the afternoon at Wembley Stadium, turning in from partner Harry Kane's low cross on 12 minutes after the lethal Englishman had opened the scoring.
Mohamed Salah threatened to inspire a Liverpool comeback when he made it 2-1, but Dele Alli's volley - and Kane's second after half-time - ensured a comprehensive win for Mauricio Pochettino's men.
Son's goal meanwhile made him the joint-most prolific Asian in Premier League history, level on 19 top-flight goals with ex-Manchester United midfielder Park Ji-Sung.
But he had opportunities - particularly in the first-half - to add to that tally and admitted his regret at not being able to make more of them.
The South Korean international told VAVEL UK afterwards: "I'm very happy. The result makes us all happy because it was so good.
"I'm a bit upset because I could have scored a couple of goals or more. I had a few big chances but the result is the main thing.
"Last season I scored a few more goals and that's why the fans expect more. I tried my best but I'm just looking at it game-by-game.
"I want to score every game but sometimes it's impossible. I just want to try and give a good performance every game and show good I am and progress every year."
Son relishes playing with "monster" Kane
Despite the manner of their win, Son was reluctant to say to suggest that it demonstrates Spurs' title credentials and that they can challenge Manchester City - who are five points ahead of the North London side after nine games.
"It's too early to say," he said. "It's just very important we take it game-by-game."
Pochettino started in a 3-5-2 formation for the second successive game, though Son making up a partnership with Kane over Fernando Llorente, and the winger admitted that he loved playing in tandem with his free-scoring team-mate.
He said: "Normally when I play with Harry I enjoy every game. He's the best player.
"I call him 'the monster' because he can score from everywhere. I'm a big fan of him. It's incredible playing with him.
"I don't mind where I play, it's just a very important thing that I'm playing. I can play as a striker, on the left, on the right, this makes me a good option for the team and I'm happy to play in any position."