Prepare the tzatziki. First, grated the cucumber on a box grater. Place in a sieve to drain. Squeeze the cucumber shreds in your hands to remove some of the excess liquid. (Use the liquid for Cucumber Water!) Combine the skyr, grated cucumber, garlic, lemon zest, lemon juice and mint. Stir to combine; set aside.
For the Meatballs: Heat the oven to 350 degrees. Line a rimmed baking sheet with aluminum foil, then set an ovenproof cooling rack on it. Coat the rack with nonstick cooking spray. Set aside.
Place the onions in a ramekin or microwave-safe bowl and microwave on medium power until soft and translucent, about 45 seconds. Set aside to cool slightly.
Combine the turkey, cooled onion, parsley, spice blend, lemon zest and salt in a mixing bowl. Stir to combine with a rubber spatula. (To taste and adjust for seasoning, simply cook a teaspoon of the mixture in the microwave on high for about 25 seconds.)
Using a small scoop, place the meatballs on the prepared rack. (It makes about 18 meatballs)
Place the meatballs on the prepared rack and baking sheet. Spritz the tops of the skewered meat with nonstick cooking spray. Transfer to the oven and cook until firm and the internal temperature registers 165 degrees on an instant-read thermometer, about 10 minutes. Serve immediately.