"Stewart's got eight goals this season and I think that's about what he should be getting," Southgate told the Sunday Sun. "Two or three years ago he got five, last year he was back down to two. One of the reasons was we didn't feel he was getting into the right areas.
"I know when he's in the right areas that he'll score because his finishing is as good as anybody's. It's being bold enough to get into those areas. We sort of highlighted (Cristiano) Ronaldo to him a bit because a lot of those things he does, his finishing and everything, but it's being in there, being far enough forward and attacking balls.
"It's getting inside your full-back when crosses are coming in from the other side of the field. Being bold really, and brave enough to say ‘Right, there's a chance of a goal here, I'm going to get in there'.
"He's done that. His goal at Anfield epitomised that because he took a chance, ran in behind the defence and with the pace he's got that's a real threat. We sat him down and said ‘Look at Ronaldo', and we showed him some video. We showed him areas we think he can get into and asked him if he'd watched clips of other players.
"Once you get a reward for the runs that you make, you think: ‘I'm going to keep getting into those sort of areas.' Hopefully that's given him that belief.
"It's no coincidence that he's now scored away from home, at Anfield, at Villa, at Tottenham. He's performing on the biggest stages against the best players. Seeing the evidence of your own eyes that: ‘Yeah I can take these people on, and if I can do it away from home against the best teams then I can certainly do it week-in, week-out.' There's no challenge that he can't take on.
"Technically he's got two great feet, he can head a ball, his work for the team is outstanding. I can't speak highly enough of him."
Or can he?
"I do think he can get better," Southgate added. "He's 23. I was still learning at 34, 35. He can get better still, no question. There's no reason why eight goals shouldn't become 10, become 12, 15. Thirty-eight would be a thing!
"He's technically-gifted enough to score goals off either foot, to score from inside the six-yard box or as we saw last week from outside the penalty area. That gives you a great opportunity to score.
"His range of talents and the way that he's progressing over the last couple of months, I think he's gone onto another level. I think he's in the best form of his career. I think what's happened with the contract is, not only does it settle his mind about things but also I think it's made him feel: ‘I am a valued member of this team, I'm not the young boy who's come through.'"