01 - Wrap the grated cucumber in a clean kitchen towel and squeeze firmly to remove excess moisture. Combine the Greek yogurt, drained cucumber, minced garlic, fresh dill, lemon juice, and extra-virgin olive oil in a mixing bowl. Season with salt and pepper, stir until smooth, and refrigerate until ready to serve.
02 - In a large bowl, combine the ground turkey, breadcrumbs, egg, minced garlic, grated onion, chopped parsley, chopped mint, dried oregano, ground cumin, salt, and black pepper. Gently fold the mixture with your hands until just evenly combined, being careful not to overwork the meat.
03 - Portion the mixture into 18 to 20 walnut-sized balls, rolling each gently between your palms to form uniform rounds. Place them on a plate or tray as you work.
04 - Heat 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 golden brown on all sides and cooked through to an internal temperature of 165°F.
05 - Preheat the oven to 400°F. Arrange the meatballs on a parchment-lined baking sheet and brush or spray lightly with olive oil. Bake for 15 to 18 minutes, turning them halfway through, until golden and cooked through to 165°F internally.
06 - Arrange the meatballs on a platter with a generous dollop of tzatziki alongside. Garnish with fresh herbs and lemon wedges. Serve with warm pita bread or a crisp side salad if desired.