Start your preparation one day before you plan to serve. First, clean your pork leg (pata ng baboy) thoroughly under running water. Using kitchen torch, carefully remove any remaining hair (balahibo) from the skin. Pat the pork leg dry with paper towels.
Take your large pot (malaking kaldero) and place the pork leg inside. Pour in one cup of white vinegar (suka), one can of lemon-lime soda, and add the crushed whole garlic head (dinurog na isang ulong bawang), whole peppercorns (paminta), bay leaves (dahon ng laurel), and two tablespoons of rock salt (asin). Add enough water to fully cover the pork.
Set your stove to high heat and bring the liquid to a full boil (kumukulo) at 100°C/212°F. Once boiling, lower the heat to medium-low, maintaining a temperature between 85-90°C (185-195°F). Let the pork simmer (pakuluan) for about 1.5 to 2 hours. You'll know it's ready when you can easily pierce the meat with a fork (malambot na), but it shouldn't be falling apart.
Remove the pork leg from the liquid and let it drain completely. Using paper towels, pat the entire surface very dry, paying special attention to the skin. Take the remaining tablespoon of rock salt and rub it all over the skin (pahiran ng asin ang balat).
Place the pork leg on a wire rack with the skin facing up. Put it in the refrigerator, uncovered, and let it dry for 8-12 hours or overnight at 4°C/40°F. This drying step (pagpapatuyo) is crucial for achieving crackling skin.
One hour before cooking, remove the pork from the refrigerator and let it come to room temperature. Meanwhile, prepare your dipping sauce (sawsawan). In a bowl, combine white vinegar, soy sauce (toyo), minced shallots (sibuyas tagalog), minced garlic (bawang), chopped Thai chilies (siling labuyo), and ground black pepper (dinurog na paminta). Mix well and set aside.
Pour cooking oil (mantika) into a large, heavy-bottomed pot - you'll need enough oil to submerge half of the pork leg. Heat the oil to 175°C/350°F. If you don't have a thermometer, test the oil by dropping a small piece of bread - it should turn golden brown within 30 seconds.
Very carefully lower the pork leg into the hot oil using long tongs or a spider strainer. The oil will bubble vigorously (bubula) - this is normal. Keep the oil temperature between 160-175°C (320-350°F). Cook for 20-30 minutes, maintaining consistent heat and occasionally rotating the pork leg for even cooking. The skin should turn a deep golden brown and become very crispy (malutong).
Remove the pork leg from the oil when the skin is crispy and golden. Let it rest on a wire rack for 10 minutes to drain excess oil and allow the meat to settle. When tapped, the skin should sound hollow and crack like candy.
Using a sharp cleaver (malaking kutsilyo), carefully chop the crispy pata into serving pieces. Serve immediately while the skin is at its crispiest, accompanied by the spiced vinegar dipping sauce and steaming white rice (mainit na kanin).
If you have leftovers, store them in an airtight container in the refrigerator for up to three days. To reheat, place in a preheated oven at 200°C/400°F for 15-20 minutes to restore the skin's crispiness (para maging malutong ulit).