Prepare the binding mixture. Heat a conventional oven to 425°F (220°C) and line two trays. Mix breadcrumbs and milk in a bowl and leave for 3 minutes. Stir in egg, two garlic cloves, oregano, 2 tablespoons parsley, ½ teaspoon salt, half the pepper, and lemon zest.

Shape twenty meatballs. Add the cold turkey and fold gently until combined. Divide into 20 equal portions and roll lightly with damp hands. Arrange on one tray rubbed with ½ tablespoon oil. Wash hands and utensils that touched raw turkey before preparing ready-to-eat foods.

Roast meatballs and vegetables. Toss zucchini and onion with 1 tablespoon oil, remaining salt, and remaining pepper on the second tray. Bake both trays for about 18–24 minutes, rotating their positions if needed. Check several large meatballs for 165°F (74°C); finish vegetables separately until tender.

Steep the couscous. Bring the broth to a boil. Stir in couscous and remaining ½ tablespoon oil, cover, and remove from the heat. Leave for 5 minutes or package-specified time. Fluff with a fork and mix in 1 tablespoon lemon juice rather than packing the grain down.

Mix cucumber yogurt. Combine squeezed cucumber, yogurt, remaining garlic, remaining 2 tablespoons lemon juice, and remaining parsley. Taste before adding extra seasoning. Divide the sauce among four small pots so it remains separate from the components that will be reheated.

Build and store the bowls. Divide couscous and roasted vegetables among four bowls and add five meatballs to each. Serve with cucumber yogurt. For meal prep, chill cooked components promptly in shallow containers. Reheat the meatballs, grain, and vegetables to 165°F (74°C) and add cold sauce afterward.