In a large bowl, mix in basil, garlic, olive oil, and lemon zest into the ground turkey. Form into half-spheres and put a mozzarella cube in the center - roll into a ball about 1 1/2” wide.
Seal in zip bags without overlapping. Use the water displacement method to seal the bags. Sous vide for an hour.
Remove from water bath and take meatballs out, season generously with salt. Heat up a cast iron on high with a little neutral oil (like grapeseed). When hot and slightly smoking, sear meatballs until there’s a nice brown crust, season with pepper to taste. Serve with your favorite pasta or as a yummy appetizer with some tomato sauce.