Blend lemongrass with garlic, shallot, cilantro roots, and 4 teaspoons of water in a food processor until smooth.
Marinate the pork with milk, dark soy sauce, cashew oil, wine, five-spice powder, Kosher salt, ground pepper, sugar, and red pepper powder. Add the lemongrass juice to the marinade.
Mix all ingredients until well combined. Let the pork marinate for at least 45 minutes.
Preheat your oven to 400°F. Grill the pork for 15 minutes.
Afterward, flip the meat and add the garlic bulb. Grill it for another 15 minutes.
Once all sides turn beautiful golden, line your baking tray with aluminum foil and transfer the pork to the tray with thyme and garlic. Wrap the pork with the foil. Make sure it covers all sides of the meat and place it back in the oven.
Lower the heat to 356°F (about 180°C) and grill the meat for an hour.