Preheat and prep: Heat the oven to 375°F (190°C). Line a sheet pan with parchment for easy cleanup.
Stir together the yogurt sauce ingredients in a small bowl and chill.
Mix the meatballs: In a large bowl, combine ground turkey, grated zucchini, onion, garlic, egg white, breadcrumbs, parsley, oregano, smoked paprika, salt, and pepper. Mix gently with a fork or your hands until just combined. Do not overmix.
Shape: Lightly oil your hands and roll the mixture into 16 meatballs, about 1.25 inches in diameter. Place on a plate.
Sear for flavor: Heat 1 tsp olive oil in a large nonstick skillet over medium-high.
Sear meatballs in batches, 1–2 minutes per side, until lightly browned. Transfer to the prepared sheet pan.
Bake to finish: Bake 8–10 minutes, or until the centers reach 165°F (74°C). Let rest 3 minutes to set the juices.
Assemble the base: Divide rice, quinoa, or cauliflower rice among bowls.
Add spinach or greens so they gently wilt from the warm grains.
Add the veggies: Top with cherry tomatoes, cucumber, bell pepper, and red onion. Add avocado if using.
Top with meatballs: Place 3–4 meatballs per bowl. Spoon over the lemon-garlic yogurt sauce.
Finish with a squeeze of fresh lemon and a sprinkle of dill or parsley.
Serve: Taste and adjust with a pinch of salt, extra lemon, or a crack of black pepper. Enjoy warm.