To make this easier and less hassle to deal with 15 riders against you for the holeshot. The achievement description stated any modes. The best way to do this method is Head to Head race.
1. Go to MUD World Tour
2. Go to Events
3. Go to Broken Bones, 4th event (head to head)
4. Your choice of a rider (doesn't matter but for starter, pick Lars "Shredder" Keller)
5. Select your gate, mine is #2
6. To make a good burn start, Hold LT (Brake) and RT (Gas), as soon as the gate drop, let the LT trigger go.
7. If done correctly, you may be able to lead or pass him to cut him off if catch up.
8. Your goal is try to beat him by passing the holeshot sign, "love my time"
9. If you done it right, the pop up will say HOLESHOT, L. Keller.
10. You can pause it and restart it to do it again. It is recorded and cumulative.
I tested it myself to see if it is cumulative by restart it after had a successful holeshot in a head to head race 15 times. It worked, took me less than 20 mins to do this. Good luck.