- To cook the pork: In a large sauce pan, heat the oil over high heat, add the strips of pork loin and cook for about 10-12 minutes or until browned, stirring frequently. Keep aside on a warm plate. 
- In a small bowl mash the avocado and mix with lime juice and salt. Keep in the fridge until ready to assemble the arepas. 
- To make the arepas: In a medium bowl add the water, arepa flour, butter and salt. Mix with your hands, making circular movements while breaking the lumps that may form with your fingers, until you have a dough. Let rest for 5 minutes. 
- Preheat a non-stick skillet over medium heat. Form balls and flatten them gently until they’re about ½ inch thick discs. 
- Place the discs on the skillet and cook the arepas for about 3 minutes on each side or until lightly golden brown. Cover them with aluminum foil to keep them warm. 
- Split each arepa in half and fill them with pork, avocado mixture, cilantro and onion slices and serve.