Cut the pork cheeks into 2" x 1" pieces (or smaller) and set aside
Chop green onions and set aside
Chop cilantro stems into ½-inch pieces and place into mortar
Pound the garlic, black peppercorns, and cilantro stems in a mortar
Heat the cooking oil in a wok over medium-high heat. Then, add the garlic, cilantro, and pepper paste to the hot oil and fry until the garlic turns golden-brown
Add the pork cheeks to the wok and fry, stirring often
Add fish sauce, sugar, MSG, and oyster sauce, and stir everything
Continue frying until the pork is cooked, about 15 minutes in total. Then, remove from heat, sprinkle green onions on top, then serve!