Mount opened the scoring in the quarter-final first leg tie, before Ben Chilwell’s effort sealed a 2-0 win to put the Blues in command ahead of next week’s second leg.
Since Tuchel replaced Frank Lampard at Stamford Bridge in January, Mount has scored five goals in all competitions, more than any other Chelsea player.
“The finish was clinical from Mason,” Tuchel told reporters. “He has the quality to do this and to do it in a quarter-final is a big step for him.
“He has the right attitude towards success. He is open and hungry to learn.”
At 22 years and 87 days, Mount also became Chelsea’s youngest goalscorer in a Champions League knockout game.
“Mason is a key player for us and I am happy he fits into this role at a young age,” Tuchel added.
Additional reporting by Reuters.