1Pat the lamb chops dry. In a large bowl or baking dish, stir together 3 tbsp of the olive oil, 4 cloves of the garlic, the zest and juice of one lemon, the rosemary, oregano, red pepper flakes, 1 1/2 tsp of the kosher salt and the black pepper. Add the chops and turn them until every side is coated. Marinate at room temperature for 30 minutes, or covered in the fridge for up to 4 hours (pull them out 30 minutes before grilling).
2While the lamb marinates, make the sauce: stir the yogurt together with the mint, the remaining clove of garlic, a squeeze of juice from a lemon wedge, 1 tbsp of the olive oil and a pinch of the remaining salt. Taste, adjust, and chill until serving.
3Set up the grill for two-zone cooking, with one side very hot (about 450 to 500°F) and one side with no direct heat. Clean the grates well and wipe them with an oiled paper towel held in tongs.
4Toss the zucchini planks with the last 1 tbsp olive oil and the remaining 1/4 tsp salt. Grill over direct heat for 3 to 4 minutes per side, until tender with dark grill marks. Move to a plate. Halve the remaining lemon wedges' worth if you like and grill 2 of them cut-side down for 2 minutes, until charred.
5Lift the chops out of the marinade and let the excess drip off. Lay them over the hot side and grill without moving for 3 to 4 minutes, until deeply browned. If flames flare up, slide the chops over to the cooler side for a moment.
6Flip and grill another 3 to 4 minutes, until an instant-read thermometer in the thickest part (not touching bone) reads 130 to 135°F for medium-rare. Thicker chops can finish on the cooler side with the lid closed for a minute or two.
7Rest the chops on a clean plate for 5 minutes, loosely covered, so the juices settle back into the meat.
8Plate the chops with the grilled zucchini, a generous spoonful of mint-yogurt sauce and lemon wedges for squeezing.