Rub pork butt with BBQ spice rub.
Add salsa into a slow cooker with diced tomato and water.
Place pork butt into the slow cooker. Set slow cooker on high and allow to slow cook for 6 hours until pork is falling apart.
After pork is done, remove pork from liquid and pull apart with 2 forks.
Remove excess fat from the pork's cooking liquid. Then transfer the liquid into a saucepan. Turn heat on high and boil for 20-25 minutes until it reduces to 1/2 the volume and coats the back of a spoon.
When sauce has reduced, mix into the pulled pork and set aside.
Make pickled red onion: add water, white vinegar, sugar, salt and mix together until salt and sugar dissolve. Add in sliced red onion and allow to sit in the refrigerator.
Make creamy cilantro dressing: add cilantro, lime juice, lime zest, yogurt, cotjia cheese, black pepper, salt, and sugar into a blender or food processor and blend until smooth. Taste for seasoning and add salt, pepper, and sugar to taste.
Assemble sliders: Spread cilantro sauce to both sides of Hawaiian rolls. Place a scoop of pulled pork onto one side of the roll. Add pickled onion, chopped cilantro, and extra creamy cilantro sauce on top of pulled pork. Top with another half of the Hawaiian bun.