Tade curled home an equaliser at the far post after losing his marker in a 2-1 win for Usuthu at King Zwelithini Stadium in Umlazi last weekend.
The 30-year-old was recruited from Auckland City, who he left as their record marksman with 107 goals in 162 outings. He won 23 trophies with the club and was thrice the New Zealand league's top scorer.
"That is the quality that we brought to South Africa and if he does this all the time then ... we know that he has the calmness," Johnson said of Tade.
"He has technique, he doesn't pack a powerful shot like 150 miles an hour but in football you don't need that. If you have an eye, calmness and the technique, you put in goals like that."
Johnson was also impressed with the all-round play of former Kaizer Chiefs and Mamelodi Sundowns forward Mabhuti Khenyeza. Khenyeza had a hand in Tade's goal, as he protected the ball before laying it off to Augustine Ramphele, whose cutback was converted by the former City hitman.
"Mabhuti had these qualities all his life," Johnson added of the 36-year-old.
"And for Mabhuti to do what he's doing at his age and to carry the team in a lot of moments ... Yes, I thought in the first half he wasn't getting those type of balls.
"In the second half he got a lot better and better. They were able to bring him in with better passing, and for that Mabhuti is always passing to guys if you use him in those positions."
Khenyeza, who made his topflight debut in 2002/03, is second on the PSL's all-time scoring list with 110 goals - 11 goals shy of teammate Siyabonga Nomvethe.