The Ghanaian, whose first three league outings this season were substitute appearances, netted in the 49th minute to make it 2-1 at Villa Park, sending the Claret and Blue Army to fifth on the Championship table.
John Terry and Stefan Johansen had earlier cancelled out each other.
"It's the best I've seen him play since I've been at the club," Bruce told pressmen.
"He was a threat all day, he ran a million miles and scored the winner - I'm delighted for him.
"I said weeks ago, he could have knocked on my door [when he wasn't starting] and said 'what's going on' but he trained every day as if it was his last.
"He's got a real spring in his step, he's enjoying playing on the left and coming inside on his right foot.
"He's now got a few goals too."
Adomah has now tallied five goals in six league starts this season, having made nine Championship appearances in all.
He also has one goal in two outings in the League Cup this campaign.
The Black Star joined the Championship side from Middlesbrough in summer last year.
He made 38 appearances involving 30 starts and three goals as the Claret and Blue Army finished 13th last campaign.