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, chopped dill, lemon juice, olive oil, and season with salt and pepper. Stir until smooth and well blended. Cover and refrigerate for at least 20 minutes to allow the flavors to meld.
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. Mix gently with your hands until just combined, being careful not to overwork the mixture.
03 - Portion the turkey mixture into 18 to 20 uniform walnut-sized balls, rolling each gently between your palms. Arrange on a plate or tray and set aside.
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 deeply golden brown on all sides and cooked through to an internal temperature of 165°F.
05 - Preheat the oven to 400°F. Arrange the shaped meatballs on a parchment-lined baking sheet and brush or spray lightly with olive oil. Bake for 15 to 18 minutes, turning halfway through, until golden and cooked through to an internal temperature of 165°F.
06 - Arrange the meatballs on a serving 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.