Arrange the leg in a large cooking pot. Pour-in water.
Add the bay leaves, lemongrass, onion, garlic, salt, and whole peppercorn.
Turn the heat on and bring to a boil. Cover and simmer until the leg is tender (60 to 90 minutes).
Remove the pork from the cooking pot. Let is cool down and dry (around 30 to 45 minutes minutes).
Preheat the oven to 475F.
Place the pata (pig leg) in a greased baking tray. Roast/bake in the oven for 45 minutes.
Remove from the oven. Brush the entire leg with fresh milk.
Put it back in the oven and continue to roast for 60 to 90 minutes, or until it reaches the desired brown color and crisp texture. You can also broil it for 10 to 15 minutes to make it more crispy.
Transfer to a serving plate. Serve with lechon sauce.