For the pork: Put the pork skin in a large pot and cover with water. Weigh down with a plate to keep it submerged. Bring the water to a boil and cook until the skin is soft and pliable but not falling apart and the water is white, 1 1/2 to 2 hours (adding more water as needed).
Carefully remove with a large spider or slotted spoon and arrange the skin in an even layer, with no folds, on a cooling rack set over a baking sheet. Discard the cooking water. Put in the fridge, uncovered, and allow to cool until completely cold, about 2 hours.
Once the skin is cold, use a spoon or bench scraper to remove all subcutaneous fat, being careful not to tear the skin. Place the scraped skin on a rack set over a baking sheet. Set the oven to its lowest possible setting (ours was at 200 degrees F) and dehydrate the skin overnight, until dry, brown and brittle.
For the spicy-sweet blend: Mix the salt, sugar and chile powder in a small bowl.
For the five-spice blend: Mix the five-spice and salt in a bowl.
For the dipping sauce: Mix the vinegar, fish sauce, chili paste and garlic in a small bowl.
To fry the pork skins: Snap the skin into small (1-inch square) pieces. Heat a deep-sided pot with about 4 inches of lard, peanut oil or a combination of the two to 385 to 400 degrees F. Fry one square at a time, prodding it until it puffs up and turns crispy, about 15 seconds. Remove to a paper-towel-lined tray and season with one of the spice blends while hot. Serve immediately or to cool to room temperature. Serve with Richmond's dipping sauce if desired.
You can also store the squares in an airtight container at room temperature for up to 2 days before frying.