“I chose to start from Grid 2, which gave me the outside line.
“Cars inside me got past over the first four laps, but I knew the track would come to me, and that the outside line would eventually pay off, and it did.”
The 25-year-old got into the lead about the five-lap mark and was never headed from there.
“We were put under a caution after a crash with five laps to go, and the field tightened up, but I eventually won it by a quarter of the home straight,” he said.
“I was rapt. It felt really good to win.
“I wasn't too disappointed with the Huntly result, but I was determined to prove how capable I am in the Grand Prix.”
Cook said it felt good to stand on the podium with his elder brother: “That's what we both strive for together.”
The brothers worked every spare hour last week to put Daniel's car back together after his crash at Huntly.
Daniel said he was “rapt” to come back so well from the New Zealand championship incident, in which another car bumped his when he was lying third in the final, and he hit the wall.
They basically had to cut the front off his car to rebuild it last week.
“To be there on the podium with my not-so-little bro' was cool,” he said.
Daniel Cook qualified seventh for the final.
“I made up a few spots early on, but by the time I had done that the lead group, which included Ethan, had pulled away a bit. But that late caution helped me.
“After the field came together again and we resumed racing, I was able to make two passes to get on to the podium.”
He was a making a pass for second place in the home straight when the chequered flag came down.
“There were only inches in it.”
The racing in the final by both Gisborne men was described as “incredible”.