Season lamb chops generously with kosher salt and set aside while you prepare the marinade. The salt will begin the tenderizing of the chops.
In a measuring cup, mix the lemon juice, olive oil, mustard, garlic, rosemary and a little additional kosher salt together. Add a generous grind of black pepper.
Arrange chops in a single layer in a glass baking dish and brush marinade on both sides, coating the chops well. Cover the baking dish with plastic wrap and marinate chops in the fridge at least an hour and up to overnight. Alternatively, you can put the chops in a zippered plastic bag and add the marinade, making sure to coat the chops, and pop that in the fridge. In either case, turn the chops at least once.
About 1/2 hour before you’re ready to put the chops on the grill, take them out of the fridge and let them come to room temperature. If you’re grilling with charcoal, do this when you light the coals.
Arrange the grill for indirect cooking; again, if you’re using charcoal, arrange the coals on one side of the grill. Lightly brush the grilling rack with oil. Remove the chops from the marinade, shaking off excess marinade, and place them on the grill away from the coals. Close the lid and cook for just a minute or so. This will let some of the marinade drip off without causing flareups.
Move chops over the coals, close the lid and cook for 3 to 4 minutes. Turn the chops, close the lid and cook for another 3 to 4 minutes. Again, keep an eye out for flareups, moving the chops if necessary.
Transfer chops to a serving platter, let them rest for about 5 minutes and serve.