In a bowl, combine the lemongrass, cilantro, mint, ginger, garlic, sugar, and lime zest. Stir in the fish sauce, soy sauce, pineapple juice, and oil. Put the chops in a large zip-top bag and pour in the marinade. Seal the bag and refrigerate for 8 hours or overnight, turning the bag occasionally.
When you’re ready to grill the chops, remove them from the marinade and drain off and discard the liquid. It’s okay if some solids adhere to the chops.
Build and light a charcoal fire with coals banked on one side only. If using a gas grill, set one side to medium high and leave the other side off. When the fire is medium hot (you’ll be able to hold your hand just above the grate for about 2 seconds), set the chops directly over the heat. Sear them for about 2 minutes per side, and then use tongs to move them to the area with no direct heat, arranging them so the bone side of the chop (if there is one) faces the heat (the bone acts as a barrier to the heat). Cover the grill and cook the chops indirectly until their internal temperature reaches 145° to 150°F, another 3 to 5 minutes per side.
Transfer the chops to a clean platter and let them rest for 5 minutes so the juices redistribute and the chops finish cooking. Sprinkle with more cilantro and mint and serve with the lime wedges.