01 - In a medium bowl, combine the grated cucumber with excess liquid squeezed out, Greek yogurt, garlic, dill, mint if using, olive oil, lemon juice, salt, and pepper. Stir until well blended, then refrigerate to allow the flavors to meld while you prepare the meatballs.
02 - In a large mixing bowl, combine the ground turkey, grated onion, minced garlic, breadcrumbs, egg, chopped parsley, dill, dried oregano, ground cumin, lemon zest, salt, and black pepper. Gently mix until just incorporated, being careful not to overwork the meat.
03 - Using about 1 tablespoon of mixture per portion, roll into 20 to 24 small uniform meatballs. Keep your hands lightly dampened to prevent sticking.
04 - For pan-frying: heat olive oil in a large skillet over medium heat. Cook the meatballs in batches, turning every couple of minutes to brown evenly on all sides, about 8 to 10 minutes until cooked through. For baking: preheat the oven to 400°F. Arrange meatballs on a greased baking sheet, drizzle with olive oil, and bake for 18 to 20 minutes until golden brown and cooked through.
05 - Arrange the hot meatballs on a platter alongside the chilled tzatziki sauce. Garnish with fresh herbs and lemon wedges. Serve with warm pita bread or a crisp salad if desired.