Prepare the slow cooker by coating it with a light coating of cooking spray.
Pat the pork shoulder dry and rub it evenly on all sides with salt, pepper, chili powder, cumin, smoked paprika, garlic powder, onion powder, and oregano.
Place the sliced onion and minced garlic in the bottom of the slow cooker.
Set the seasoned pork on top of the onions.
In a small bowl, whisk together the lime juice, chicken broth, and brown sugar, then pour the mixture around the pork.
Cover and cook on Low for 8 hours or High for 5 hours, until the pork is fork-tender and easily shreds.
Remove the pork from the slow cooker and shred it with two forks, discarding excess fat.
Return the shredded pork to the slow cooker and stir it into the cooking juices, then let it sit for 10 minutes to absorb flavor.
Warm the tortillas in a dry skillet or directly over a gas flame until pliable.
Fill each tortilla with pulled pork and top with your desired toppings before serving.