Combine the chiles, garlic and cilantro in a small bowl and mix well. Heat the oil in a wok, swirling to coat the surface, add the chili mixture and stir-fry until garlic is aromatic, about 1 minute. Add the pork and stirfry, stirring often, until meat is cooked, about 5 minutes. Add the oyster sauce, fish sauce, sugar and chicken stock, toss and stir to combine and heat thoroughly. Stir in the basil leaves and immediately serve over rice.