Heat the cooking oil in a wide thick-bottomed pan. Lower the pork in the hot oil, skin side down (watch out as the oil will spatter) and cook over high heat until the skin is well browned. Flip the pork belly over and brown the opposite side. Scoop out the pork belly and set aside.
Reheat the remaining oil in the pan. Add the black bean sauce, oregano, garlic, shallots, cinnamon, star anise, peppercorns and palm sugar. Pour in the rice wine. Swirl the pan around and allow the mixture to boil for a minute or two (watch carefully to prevent the sugar from burning).
Push the spices and herbs to the sides of the pan. Lower the pork belly carefully back into the pan, skin side up.
Pour in the broth and soy sauce. Bring to the boil, set the heat to low and simmer for an hour. Flip the pork belly over and cook for 45 to 50 minutes. Turn off the heat. Leave the pork to soak in the sauce for another 15 minutes.
Take the pork belly out of the pan and lay on a cutting board. Leave until cool enough to handle. Cut the pork belly into slices (thick or thin, that's up to you) and arrange on a serving plate.
Strain the broth and boil until reduced by half. Taste. Adjust the seasonings, as needed. Pour the sauce over the sliced pork belly.