Whisk together the soy sauce, oyster sauce, cilantro, garlic, sugar, and black pepper in a bowl.
Skewer 2 pieces of pork onto 2 skewers so that the meat lies flat. Place the pork skewers in a large baking dish. Pour the marinade over and turn to coat the pork. Cover and refrigerate for at least 1 hour and up to 4 hours.
Heat grill to high. Remove the skewers from the marinade and grill the meat on both sides until slightly charred and cooked through, about 3 minutes per side. Serve with Chili Sauce on the side for dipping.
Combine all ingredients in a small bowl. Cover and let sit at room temperature for at least 1 hour before serving.