Luis Diaz, Cody Gakpo, Mohamed Salah, Trent Alexander-Arnold and substitute Diogo Jota struck on the night for the visitors.
A delighted Slot declared afterwards: "I like to see this because if you only rely on one player when it comes to goals that is mostly not really helpful, although it's also nice to have one that scores a lot. But then to see that others score goals and threatening the other goal as well is pleasing to see.
"It's not only the one that scores the goal, I think the lead-up towards the goal is also very positive from our point of view.
"The way I would like to see us play an away game. I think it's always, especially in the Premier League, the defence come with a lot. There's a lot of fans in every stadium we play. The stadium is always sold out if Liverpool comes. They don't need much to cheer for if Liverpool comes in because if they already have an attack, or a corner kick, the fans are already cheering, so then you have to kill that momentum as much as you can and not give away anything.
"I think there was only two, three or four minutes where Curtis (Jones) lost the ball, Mo lost the ball and then we conceded a corner, which probably wasn't a corner, where the fans were a bit behind West Ham. For the rest, I think because we were so dominant we could manage West Ham but also the crowd."