Step 1: Make the rub: Place the garlic, coriander roots or cilantro, fish sauce, salt, pepper, and coriander in a food processor and finely chop. Add the lime juice and enough vegetable oil to obtain a thick paste. Alternatively, pound the dry ingredients to a coarse paste in a mortar and pestle, then work in the lime juice and oil.

Step 2: Prepare the ribs: Remove the thin, papery membrane from the back of each rack of ribs. Turn a rack meat side down. Insert a sharp implement, such as the tip of a meat thermometer, under the membrane (the best place to start is right next to the first rib bone). Using a dishcloth or pliers to gain a secure grip, pull off the membrane. Repeat with the other rack.

Step 3: Place the ribs on a rimmed baking sheet. Using a rubber spatula, spread the wet rub on both sides. Cover the ribs with plastic wrap and marinate in the refrigerator for at least 2 hours, or as long as overnight—the longer, the richer the flavor.

Step 4: Set up the grill for indirect grilling and preheat to medium. Brush and oil the grill grate.

Step 5: Arrange the ribs, bone side down, in the center of the grate over the drip pan away from the heat. Cover the grill and cook until ribs are well-browned and cooked through, 1-1/4 to 1-1/2 hours. When ribs are cooked, the meat will have shrunk back from the ends of the bones by about 1/4 inch.

Step 6: Brush the ribs on both sides with chili sauce. Move the ribs directly over the fire. Grill until the sauce is sizzling and browned, 2 to 3 minutes per side. Watch carefully as the sugars in the chili sauce can scorch easily.

Step 7: Transfer the ribs to a large platter or cutting board, and cut the racks in half, widthwise. Brush the ribs with more chili sauce and sprinkle with finely chopped peanuts. Serve any remaining chili sauce on the side.