Place pork skin in a large pot, and cover with water. Weigh down the skin with a heatproof plate to keep it fully submerged. Bring water to boil over high, and cook until skin is soft and pliable, but not falling apart, about 2 hours.
Carefully remove skin from pot, and arrange in an even layer, with no folds, on a wire rack in a rimmed baking sheet. Chill, uncovered, until completely cool, about 2 hours.
Preheat oven to 175°F. Using a sturdy heavy spoon, scrape and remove all fat under skin, being careful not to tear the skin. Place scraped skin on a wire rack on baking sheet. Bake in preheated oven until skins are dehydrated, dry, brown and brittle, about 8 hours.
If using, stir together chile powder, cumin, and salt in a small bowl; set aside. Otherwise, just have salt on hand. You will be using this to season the Chicharrón after frying them.
Heat 4 inches of oil in a Dutch oven, to 400°F. Break dried skins into about 1-inch pieces. Fry skin pieces in hot oil, 3 at a time, prodding pieces until skins puff up and turn crispy, about 15 seconds. Transfer to a plate lined with paper towels; sprinkle with chile powder/salt mixture, or plain salt.
Repeat procedure with remaining skin pieces.