These are steaks, which you would fry or grill, but from the leg, which you would roast. So how to cook them? I chose a compromise.
The marinade includes a garlic clove, crushed with salt; the juice of half a lemon; and about three tbsps of olive oil. The steaks sat in it for only half an hour.
I got a ridged grill pan very hot, scraped excess marinade off the steaks, and seared them (one at a time) for only a minute each side, just long enough to give them a griddled appearance. I returned them to the marinade in the oven dish, and roasted them for 30 minutes at gas mark 6/200C. Those who prefer their lamb to be less well done could allow at least 10 minutes fewer.
As you can see, they produced a fair amount of sauce.