Rinse ribs with running water and transfer to large pot. Add water to cover ribs. Add shaoxing wine, ginger, green onion, star anise and pepper to the pot. Cover and bring to a boil. Uncover and continue to cook for 5 minutes. Use a ladle to skim the foam from the surface and discard it.

Mix black vinegar and light soy sauce in small bowl, set aside.

Add oil and sugar to a wok and cook over medium heat. Stir constantly with a spatula to dissolve the sugar slowly. When the sugar is fully dissolved, use spatula to scoop some liquid mixture to observe its color. When the sugar turns pale yellow, immediately and carefully add the ribs to the wok. Stir constantly to coat them well with melted sugar. Stir until the ribs turn golden brown, turn off heat.

Transfer the ribs to a plate. Use spoon to scoop out the extra oil and transfer it to a small bowl, until there is only about 1 tablespoon of oil left.

Turn heat to medium high. Return ribs to the wok. Pour the vinegar and soy sauce mixture over the ribs and quickly stir to mix well. Continue to stir until the sauce has reduced and is thick enough to coat the ribs. Stop heat immediately and transfer the ribs to a plate.

Garnish the ribs with chopped green onion.