Prep the chops. Pat dry. If any chop is much thicker than the others, pound the thick ones gently to even them out — even thickness cooks evenly. Score the fat cap lightly so it does not curl on the grill.
Marinate. Whisk the lemongrass, garlic, shallot, fish sauce, sugar, oil, and pepper in a large shallow dish. Add the chops, turn to coat, cover, and refrigerate. Marinate at least 2 hours; overnight is preferred. Thicker meat needs more time than thin slices.
Bring to room temperature. Take the chops out of the fridge 25 minutes before cooking so they cook evenly.
Grill or sear. Medium-high heat, oiled grates or a hot skillet with a thin film of oil. Cook about 5 minutes per side — resist moving them around so the surface caramelizes. If the sugar starts to burn before the inside is done, move to indirect heat or finish in a 375°F oven.
Check doneness with a thermometer, not by color. Pork chops must reach 145°F (63°C) internal temperature, measured in the thickest part away from bone. Then rest 3 minutes before serving — the temperature holds and the juices settle.
Serve over rice with pickles and nuoc cham on the side.