Score the pork skin with a sharp knife at 1cm intervals.
Rub the pork with oil and salt.
Roast at 160°C (320°F) for 2.5 hours.
Increase the temperature to 250°C (485°F) for 30 minutes to achieve crackling.
Mix diced roasted red bell peppers with finely minced serrano chilies, diced avocado, red onion, fresh cilantro, and lime juice for the salsa.
For an alternative sauce, dissolve 1 cup white sugar, ¼ cup fish sauce, and ¼ cup water with ginger, garlic, and chilies, simmer until reduced.
Let the pork rest for 10-15 minutes before slicing or cubing.