Rub the lamb all over with 1/4 cup of the olive oil and set aside.
In a small bowl, mix together the panko, rosemary, mustard, garlic, the remaining 2 tablespoons of olive oil, the vinegar, salt, and pepper. Blend thoroughly to make about 1 cup of paste.
Spread the paste over the meaty side of each rack. This will form a crust so make sure to coat the racks evenly, spreading it over the meaty portions but not covering the bones. Set aside, loosely covered with foil, while the grill heats.
Prepare a charcoal or gas grill: Lightly spray the grill rack with vegetable oil cooking spray. Light the coals or heating elements, and let them burn or heat until moderately hot.
Lay the racks on the grill, crust side down, and cook for 3 to 4 minutes, until aromatic and grill marks form on the crust. Using tongs or a wide spatula, carefully turn the racks over. If a little of the crust slides off, lift it off the grill and push it back in place.
Cover the grill and cook for 15 to 20 minutes longer, depending on the thickness of the meat, until an instant-read thermometer inserted in a meaty portion of a rack registers 140°F for medium-rare, or until the meat is cooked to the desired degree of doneness. Move the meat around on the grill to ensure even cooking but don't turn it again. Let the racks rest for 5 minutes before cutting between the ribs into individual chops for serving.