In a medium mixing bowl, combine the ground lamb, minced garlic, finely chopped parsley, cumin, coriander, cinnamon, half the sea salt, and half the black pepper.
Mix the meat and spices by hand until just combined, being careful not to overwork the meat which can make it tough.
Divide the mixture into four equal portions and shape them into long, oblong cylinders around wooden or metal skewers.
Preheat a cast-iron grill pan or outdoor grill over medium-high heat and lightly coat with a touch of oil spray if needed.
Grill the koftas for 3-4 minutes per side, or until they reach an internal temperature of 160°F and have a nice charred exterior.
While the meat cooks, prepare the sauce by whisking together the Greek yogurt, finely chopped mint, lemon juice, and the remaining salt and pepper in a small bowl.
Dice the cucumber and thinly slice the red onion to create a simple base salad.
Plate the hot lamb koftas over the cucumber and onion mixture and serve immediately with a generous dollop of the mint yogurt sauce.