This can be done in any event type in Career mode. The event types are Race, Rivals, Exploration and Trick session. Mostly likely you will get this from winning a race because in the beginning, not much is unlocked. First time you get a Gold medal for winning the event, the achievment will pop. I got it on the first try, but if your not good at this type of game, it might take a few tries. Just keep trying and leveling up. Upgrading your bike under 'Garage' also helps. Good luck!