In a large mixing bowl, combine the ground turkey, zucchini, carrot, bell pepper, onion, garlic, breadcrumbs, Parmesan cheese, egg, Italian seasoning, salt, black pepper, and crushed red pepper flakes (if using).
Mix the ingredients using your hands until just combined; be careful not to overmix.
Form the mixture into 1-1.5 inch meatballs and place them on a baking sheet lined with parchment paper.
Bake the meatballs in the preheated oven for 20-25 minutes, or until they are cooked through and golden brown.
While the meatballs are baking, heat the marinara sauce in a saucepan over medium heat.
Once the meatballs are done, remove them from the oven and add them to the saucepan with the marinara sauce. Allow them to simmer gently in the sauce for about 5 minutes to absorb the flavors.
Serve the veggie-loaded turkey meatballs over pasta, rice, or in a sub roll, garnished with fresh basil if desired.
Notes
Ensure to squeeze out excess moisture from zucchini for better texture.