Nothing pitches me headfirst into gloom faster than Labor Day. I will chirk up once it’s October—always such a golden month—but for now, I am holding on tight to summer. The peaches are wonderful. The tomatoes are delicious. The corn—even that bought on the fly in a suburban supermarket—is juicy and full of farm-stand flavor.

This Labor Day, reason to live came in the form of a lamb steak, a cut usually taken from the center of the leg and sporting a cross-section of bone similar to that of a ham steak. Because it responds beautifully to marinades or rubs in every flavor palette imaginable and because it cooks so quickly, it’s outstanding on the grill or under the broiler. This is nothing new—James Beard wrote about grilling lamb steaks with great relish in the July 1956 issue of House & Garden—but it has never been as popular as it deserves to be.

Baffling, really. A lamb steak is more flavorful and less expensive than loin or rib chops and not as fatty as shoulder chops. And for a household of two, in which a leg of lamb (even a “short” leg, minus the wider top section) is overkill, a 1½-pound-plus lamb steak is just right for one meal and satisfying day-after sandwiches.

Lamb steak is at its best when not cooked past medium. “Grill over coals, turning to brown evenly,” writes Mr. Beard, “until the steaks are nicely browned on the outside but still pink and rare in the middle. Season to taste with salt and pepper as they cook.”

One simple thing you can do with grilled lamb steak is cut it into succulent, rosy slices and serve it with warmed pitas or other flatbread, leaves of crisp romaine, and the cool, creamy cucumber-yogurt condiment called tzatziki. Even if the people at your table cannot stand yogurt, they will love tzatziki, and you will always wish you’d made more.

For inspiration this past weekend, however, I looked no further than the herb garden we’ve had fun with all summer. It looked a bit worse for wear after Irene roughed things up, but Mediterranean herbs thrive on drama. I chopped up small, fragrant handfuls of rosemary, thyme, marjoram, and summer savory and stirred them together with salt, some chopped garlic, and olive oil. Then I smeared the slurry all over the steak and left it alone for an hour. That gave me plenty of time to size up the tomatoes we had on hand.

They were nice and big, but misshapen—not the best candidates for classic tomatoes Provençal, which are sliced through the equator so each half will stand upright, cradling a raft of seasoned breadcrumbs. It didn’t matter. I cut the tomatoes into as even slices as I could manage, then overlapped them in a small oiled gratin dish. Scattered with a mixture of lightly toasted fresh bread crumbs, grated Parmigiano-Reggiano, and olive oil, they would take no time in the oven.

I extricated some leftover boiled potatoes and stewed romano beans—you know, the flat green ones—from the fridge and warmed them up together. The only romanos I’d been able to find at the market were mature—broad and bumpy with developed seeds inside. I’d cooked them until tender the first go-round, and, after being reheated, you could cut them with a fork. They had great depth of flavor. The potatoes were tender, too, yet still held their shape. This was going to be good.

Grilling a lamb steak is easy. If flare-ups bother you, then trim off some (but not too much) of the excess fat. As you would with beef steak, gauge the cooking time by thickness, not by weight. Ours, just over an inch thick, took about 10 minutes for medium-rare, just long enough to finish a bowlful of black olives, lick the oil off our fingers, and open another bottle of wine.

We left the steak a bit longer on the first side to develop a good sear before turning it over. The tomatoes had gone into a hot oven—450º or so—right before the steak hit the grill rack. By the time the meat was off the fire and had a chance to collect itself, the tomatoes were bubbling and their topping was golden brown. The beans and potatoes were getting along famously. Everything smelled absolutely wonderful.

By the time we sat down to eat, I had forgotten it was September. Until I received a text from my friend Thomas Jayne, who shares my end-of-summer angst. “Worse than a back to school advert …” he wrote. “is ‘Book your Christmas party now!’ “