Place the pork leg in a snuggly fitting pot. Add salt, peppercorn, garlic, onions and bay leaves. Pour in the water ad bring to a boil over high heat.
Once it starts to boil, cover the pot and bring the heat down to low. Let it simmer for 1 hour or until meat and skin is tender but not too tender. You may add some water in between if it starts to dry up and the leg is not cooked yet.
Remove the pork leg from the pot and drain excess liquids. Place it on a rack over a pan so the liquids can drip easily. Let it rest for 30 minutes.
Brush the skin part completely with lye water. Place the leg in the fridge uncovered for at least 5 hours or overnight.
Brush the skin this time with vinegar then rub some salt all over. Rest again for 30 minutes then use a kitchen or paper towel to remove the salt from the skin.
Heat oil in a large, deep pot over medium-high heat. Once the oil is hot, gently add the pork leg and cover the pot. Wait until the splattering sounds subside a little and remove the cover. Replace the lid with a splatter screen if you have it.
Fry the pork leg until the skin becomes crispy Turn as needed to get all the skin to cook until they crackle. Takes about 30 minutes to cook all sides and maybe lesser if completely submerged in oil.
Transfer to a plate with paper towels to drain excess oil. Serve with vinegar-soy sauce dip while still warm and enjoy.