Here is another recipe for the slow cooker. It is adapted from Mozza restaurant in Los Angeles. The recipe says to roast it in the oven, but I would use a crockpot instead. I think it would be very good served with corn tortillas.
Roast Pork Butt With Salsa Verde
Adapted from Mozza restaurant, Los Angeles
7- to 8 lb pork butt, fat cap (preferably 1-inch thick) attached
3 1/2 tablespoons salt, plus more for salsa
1/4 cup coarsely ground black pepper
2 cups extra virgin olive oil
6 to 8 tablespoons sherry vinegar
4 cups chopped fresh parsley
2 cups chopped fresh oregano
8 garlic cloves, peeled
Pinch of red pepper flakes
Ground black pepper
Heat oven to 200 degrees. Season the pork with 3 1/2 tablespoons of salt and 1/4 cup black pepper, rubbing it in well on all sides. Roast the pork until the internal temperature reaches 195 degrees, 9 to 10 hours. While the pork is roasting, prepare the salsa verde.
In a blender or food processor, working in batches if necessary, combine the olive oil, 6 tablespoons of the vinegar, parsley, oregano, garlic and pepper flakes. Process to a purée, and transfer to a mixing bowl. Season with salt, ground black pepper and more vinegar to taste.
To serve, pull the pork apart with tongs or forks or slice it. Serve with the salsa.