01 - Wrap the grated cucumber in a clean kitchen towel and squeeze firmly to remove all excess moisture. In a mixing bowl, combine the Greek yogurt, drained cucumber, minced garlic, dill, lemon juice, and extra-virgin olive oil. Season with salt and pepper, then stir until fully incorporated. Cover and refrigerate to allow the flavors to meld while you prepare the meatballs.
02 - In a large mixing bowl, combine the ground turkey, breadcrumbs, egg, minced garlic, grated onion, parsley, mint, dried oregano, ground cumin, salt, and black pepper. Gently fold the mixture with your hands until just combined — avoid overworking the meat to keep the meatballs tender.
03 - Using damp hands, portion the mixture and roll into 18 to 20 uniform walnut-sized meatballs. Place them on a plate or tray lined with parchment paper.
04 - Heat the olive oil in a large nonstick skillet over medium heat. Working in batches to avoid crowding, add the meatballs and cook for 8 to 10 minutes, turning every couple of minutes, until deeply golden brown on all sides and cooked through to an internal temperature of 165°F. Alternatively, bake in a preheated 400°F oven on a parchment-lined sheet pan, brushing the meatballs lightly with olive oil, for 15 to 18 minutes, turning halfway through.
05 - Arrange the cooked meatballs on a serving platter and spoon a generous dollop of tzatziki alongside. Garnish with fresh parsley or dill sprigs and lemon wedges. Serve with warm pita bread or a crisp side salad if desired.