Luis Suarez scored a double while Henderson was also on a scoresheet that included Jon Flangan and Raheem Sterling.
A chastening day for Spurs and their boss Andre-Villas Boas was made worse by the dismissal of Paulinho for a high boot on Suarez.
"It was fantastic," Henderson told Sky Sports 1.
"We knew we had to come here and put in a good performance and get a good result. Thankfully we did that and we played unbelievable."
Liverpool's performance was made even more impressive at it was achieved without skipper Steven Gerrard and striker Daniel Sturridge due to injury.
Gerrard watched on in the Sky Sports studio and afterwards declared his side now had the confidence to challenge for the Barclays Premier League title.
"Of course we are a title contender," he said.
"There's still a long way to go - a lot of big games and hurdles to come over before we become real title contenders.
"We will take a lot of belief from this."
Gerrard labelled the performance the best under boss Brendan Rodgers, adding: "I'd say it was Brednan Rodgers' best game for Liverpool.
"I think it was Jordan Henderson's too. There's no rush (for me to return from injury)."
Suarez's white-hot form has vindicated the club's decision to keep him in the summer, and Gerrard said he was certain the Uruguayan will help the Reds make a return to the Champions League stage the striker himself craves.
"Luis is key to that," he said.
"If he keeps playing like that there's no doubt we'll finish in the top four. That's what Luis wants."
Suarez praised his team-mates, adding: "We played very well.
"I try my best on the pitch and I am striker so I try to score. But most important was the performance of the team and we played very well in the first half.
"I'm so happy for us."
Rodgers agreed with Gerrard that the performance was the best since he arrived at Anfield.
"It was fantastic," he said. "It was everything that we wanted out of the game - in terms of how we operated and pressed the ball. That earned us the right to play.
"The quality of football - we scored five goals and probably could have had seven or eight.
"It was probably the most complete performance since I've been here."
The Northern Irishman refused to get carried away into talk of winning titles when asked if his objectives had now changed: "No. Not really.
"We just want to continue to improve. Today was great from that perspective. I really enjoyed watching my team today from every aspect."
Villas-Boas took the blame for a defeat that is likely to again revive talk over his position.
The Portuguese was under the spotlight following last month's 6-0 defeat at Manchester City, after which Spurs had been unbeaten until Sunday.
"It was difficult for us, Liverpool were spectacular today," he said. "They made really good pressing and couldn't let us play.
"Our response came in the second half but when we fell short of Paulinho the game was difficult to turn. Liverpool started dominating possession and putting balls in behind.
"We struggled. I assume the responsibility of the failure.
"We have to bounce back like we did after City.
"In the Premier Lgague things are not going as we expected. It is normal that frustration is there from everybody."
Asked if he feared for his own position, Villas-Boas claimed that he did "not need to convince anybody".
"Regarding my position it's not me who decides. I can only work to make things better," he said.
"We didn't have any shots on target today. We are the team with the most shots in the Premier League independent of our poor goalscoring record. Today it wasn't to be because Liverpool had a great, great game.
"Again I assume the responsibility of the failure.
"I don't need to convince anybody.
"Our run is magnificent in other competitions, but not in the Premier League. That is the reality that we face."
Villas-Boas also suggested Paulinho's sending-off was the key moment in the game and that injuries in his squad had played a part.
"It was difficult after the sending-off. That was our best period," he said.
"I think the sending-off is a bit unfair. I agree that Paulinho raises his feet high but has no intention to take it on Saurez. I think yellow was appropriate.
"That was the key moment in the game and didn't give us a chance to hit back.
"The reality is we have had some injuries which have forced us to adapt. But we assume that we can do better. It is up to us once again to give a response as we should."