Rinse your pork belly and use a tweezer to remove any hair on the skin. Rinse your pork belly again and cut it into 1.5-inch strips. Pat-dry thoroughly with paper towel and set aside. Patting it dry is to make sure the oil won't spit and spatter later on.
Heat oil over medium heat in a pot large enough to put the pork belly in a single layer. Rinse your garlic, pat-dry then add it into the oil (no need to crush or peel). Cook for 2 to 3 minutes then add in the pork belly strips in a single layer. Turn the heat up to medium-high and sear all sides of the pork belly (including the skin) until lightly golden, about 5 minutes.
Add in the dark soy sauce and just enough water to cover the pork belly. Crank up the heat and bring the water to a boil. Reduce the heat and simmer for 2 to 2.5 hours, turning the meat every 30 to 45 minutes to colour it evenly. Top up water if necessary (especially if you are braising it for 2.5 hours).
After 2 hours (or 2.5 hours) of simmering, the sauce should have reduced into a slightly thick consistency - turn off the heat and cool slightly before slicing the pork. If the sauce is not thick enough, remove the pork belly from the pot, turn up the heat and boil until the sauce has reduced and thickened.
Transfer the sauce into a small bowl and serve it together with the braised pork.
You can add up to 2 tablespoons of soy sauce but drizzle sparingly as the sauce will be more salty.
Cut a slice and taste the meat after 2 hours of braising - if it's not soft enough to your liking, braise it longer.