Serves: Makes 6 servings
- 2 pounds freshly ground lamb shoulder
- 1 tablespoon plus 1 teaspoon dried oregano
- Kosher or sea salt and freshly ground black pepper
- ½ teaspoon hot red pepper flakes
- 6 red onion slices, ½ inch thick
- 1 tablespoon extra virgin olive oil
- 1⁄3 pound Greek, French, Bulgarian, or Israeli feta cheese, at room temperature, crumbled
- 6 hamburger buns, split
- Ground sumac (optional)
- 2 tomatoes, thinly sliced
- Feta cheese (optional)
Prepare a moderate charcoal fire for indirect grilling or preheat a gas grill to medium (3751⁄4 to 400°F), leaving one burner unlit.
Put the lamb in a large bowl. Add the oregano (crumbling it between your fingers as you add it), 2 teaspoons salt, and hot pepper flakes, and season with black pepper. Work the seasonings in gently, then, with moistened hands, shape the meat into 6 patties each about 3⁄8 inch thick. They should be a little wider than your hamburger buns, as they will shrink in diameter when cooked.
From opposing directions, insert 2 toothpicks horizontally into each red onion slice; the toothpicks will hold on both sides with some of the olive oil and season with salt and pepper.
Grill the onion slices first: Place them directly over the coals or gas flame and cover the grill. Cook, turning once, until nicely colored on both sides, about 5 minutes, then move to indirect heat until they are softened but not limp, about 5 minutes longer. Keep warm while you grill the burgers.
Grill the burgers directly over the coals or gas flame-lid off on a charcoal grill, lid on for a gas grill. Cook until they are done to your taste, which you can best determine by touch. A rare burger feels soft, with no spring back. A medium burger will offer some resistance to the touch, but will not feel firm. A well-done burger will be firm to the touch. Cooking time depends on the heat of your fire, but a medium burger will take about 10 minutes. A couple of minutes before the burgers are done, top with the feta, dividing it evenly, and toast the bun halves on the grill, cut side down.
To assemble the burgers, place the bottom halves of the buns, cut side up, on individual plates. Sprinkle generously with sumac. Top with tomato slices and sprinkle with salt. Remove the toothpicks from the onion slices and place on top of the tomato. Top the onion with a burger, sprinkle with feta cheese and sumac, then cover with the top half of the bun. Serve immediately.