The six-furlong event was the daughter of Hennessy's first try over a synthetic surface. She adjusted to the Toronto oval's Polytrack with style, defeating onrushing Ontario-bred Lucas Street by 1 1/2 lengths.
The Chicago-based mare Miss Macy Sue, who set the pace, was third.
"I wanted to play it by the break and see how it was going to go from there," said winning jockey Channing Hill. "Everyone left the inside open for me, which I didn't really understand. I took advantage of it. She ran through there really nice."
The Ontario Fashion was Hill's second victory aboard the Kentucky-bred, who is owned by Johanna Murphy-Leopoldsberger.
"When I broke her maiden, I really liked her. She did it the right way, in the right style. She proved it by coming back and winning (the Open Mind)," recalled Hill. "She was always cut out to be a nice filly."
Trainer David Duggan said the three-year-old filly came back with an excuse after her most recent start, an 11 1/4-length defeat to Indian Blessing in the Grade 2 Gallant Bloom at Belmont Park.
"She had a legitimate excuse. She came out of the race with a stone bruise," said Duggan, whose last Woodbine attempt came in the 2006 Flaming Page with sixth-place finisher Moon Dolly. "She's a very good filly. She's got a high cruising speed and you can place her wherever you want to."
The Ontario Fashion was the fifth career victory from nine starts for Porte Bonheur, who won the Grade 3 Victory Ride over talented filly Indyanne.
Porte Bonheur returned $15.50, $8.10, $4.90, combining with Lucas Street ($9.60, $5.30) for a $96.30 exactor. Miss Macy Sue ($3) rounded out a triactor worth $287.30. Marina Ballerina completed a $1 superfecta worth $1,436.25.