For the burgers: Combine the ground lamb, garlic, salt, cumin, smoked paprika, oregano, cinnamon, pepper, and 2 tablespoons olive oil in a large bowl. Gently mix the lamb mixture to thoroughly combine with the seasoning. Divide the mixture into 4 even portions, about 8 ounces each. Pat each portion into a ball (but not too tightly), then press into 1-inch thick patties.

To cook on the stovetop: Heat a large cast-iron skillet over medium-high heat. Add the remaining 2 tablespoons of olive oil and swirl to coat the pan. Place the patties in the skillet and let cook for 3 to 4 minutes until golden and crusty. Flip and cook the other side until the internal temperature of the burger reaches 135˚ (for medium doneness), about 3 more minutes. Let rest for 5 minutes.

To cook on the grill: Preheat the grill over medium-high heat, 400 to 425˚. Oil the grill grates. Place the patties on the grill over direct heat. Cook for 3 to 4 minutes per side, covered, or until the internal temperature reads 135˚ (for medium doneness). Let rest for 5 minutes.

For the feta sauce: While burgers rest, stir together the yogurt, cucumber, feta, and mint in a small bowl. Taste, and season with salt if you like.

To assemble: spoon a tablespoon of the feta sauce on each bottom bun. Add arugula, sliced tomato, 1 lamb patty, more feta sauce, red onion, and then the bun top. If you like, spear pepperoncini peppers, cubes of feta, and kalamata olives on 5-inch wooden skewers and add one to each assembled burger.