Wash the pork belly thoroughly under cold water and pat it dry. Then cut it into coarse, bite-sized pieces and put them in a bowl.
Peel the garlic cloves and chop them very finely. Also chop the lemongrass very finely (it's best to only use the lower, more tender part).
Add the chopped garlic, finely chopped lemongrass, dark soy sauce, oyster sauce, the juice of half a lemon, chili powder, and honey to the meat in the bowl. Season with pepper and salt to taste.
Mix everything thoroughly so that the meat is completely covered with the marinade. Make sure all spices are well distributed.
Cover the bowl and place it in the refrigerator for at least one day (or ideally overnight) so that the meat can absorb the flavors well.