Arrange the minced onion at the bottom of the crock pot.
Lay-in the pork shoulders. You can divide the pork shoulders in half if it does not fit the crock pot.
Combine salt, pepper, sugar, vinegar, garlic powder, and Sriracha sauce in a bowl. Mix well. Pour the mixture in the crock pot. Cover and slow cook for 7 hours.
Remove the pork and let cool. Shred the pork using your hands. Set aside.
Transfer the remaining liquid in a sauce pan. Cook the liquid and reduce in half. Pour over the pulled pork crock pot.