Combine the garlic, lemon, mint and cucumber in a small bowl and stir the mixture. Add the yogurt and stir to combine. Cover and chill until ready to serve.
Preheat oven to 375 degrees. Prepare two baking sheets - line them with tin foil and spray with vegetable spray.
Heat 1 tablespoon olive oil over medium high heat in a medium skillet. Add the onions and a pinch of salt and cook until translucent. Transfer onions to a large bowl.
Add the remaining tablespoon of olive oil to the skillet and add the grated zucchini. Sprinkle with a pinch of salt and cook until zucchini is wilted and softened - about 5 minutes. Transfer zucchini to the bowl with the onions. Add the capers and sun-dried tomatoes and stir to combine.
Place the bread in the bowl of a mini prep food processor and pulse until you have fine bread crumbs. Add the parsley and pulse several times until parsley is chopped and well combined with the bread crumbs. Transfer bread crumbs to the bowl. Add the egg, garlic, kosher salt, black pepper, worcestershire sauce, parmesan cheese and mint to the bowl and stir.
Add the turkey meat and using your hands work the turkey into the binder until well combined. Scoop out a tablespoon of turkey mixture and roll it between your hands to form a meatball. Place the meatballs on the cookie sheet about 1 inch apart. Bake for 20-25 minutes until lightly browned and cooked through.
Transfer the meatballs to a platter and serve the tzatziki on the side.
For meatball sliders, cut small dinner rolls in half. Add arugula to the bottom half of the roll. Top it with a meatball, a dollop of tzatziki and the other half of the roll.