Begin by seasoning the outside of a pork butt with about ½ tablespoon salt and ½ tablespoon pepper. Add neutral oil to a cast iron skillet and place pork butt inside. Braise the butt until each side has some color to it and the exterior of the meat starts to crisp up - this will add to the depth of flavor. Once the pork butt is browned on all sides, transfer it to the crock pot.
Add OJ, lime juice, lemon juice, olive oil, garlic, and oregano on top and cover. Turn the heat to medium and cook for 8 hours until the meat starts to fall apart and shreds easily. Set meat aside.
For the Sandwich
Begin by laying half the cheese onto one slice of bread. Top it with the mojo pulled pork, cilantro, the rest of the cheese and the top piece of bread. Butter the exterior of the sandwich and set aside.
Using either a panini press or a cast iron skillet, turn the heat to medium and cook the grilled cheese until both sides are golden and crispy and all of the cheese has melted.
Remove it from heat and set aside for a minute to rest. Slice the sandwich and serve immediately with avocado salsa if desired