With a mortar and pestle (or a bowl with a wooden spoon), smash garlic, shallot, salt and pepper to make a paste. Put in a large bowl and add oyster sauce, soy sauce and sugar/honey stir to combine.
Add chicken and marinate at least an hour. Grill or broil. Serve with rice and vegetables.
Notes
For pork add 1 tablespoon of minced ginger with the shallots and garlic and 2 tablespoons of vinegar with the other liquids.