Make the Meatballs: Preheat oven to 400°F. In a bowl, mix turkey, breadcrumbs, egg, garlic, parsley, oregano, salt, and pepper until combined. Form into small meatballs. Heat olive oil in a skillet over medium heat and sear meatballs for 2–3 minutes per side until golden. Transfer to a baking sheet and bake for 10–12 minutes until cooked through.
Cook the Couscous: Bring chicken broth, olive oil, and salt to a boil. Stir in couscous, cover, and remove from heat. Let sit for 5 minutes, then fluff with a fork.
Prepare the Salad: In a bowl, combine cucumber, tomatoes, red onion, feta, olive oil, red wine vinegar, dill, salt, and pepper. Toss well.
Make the Sauce: In a small bowl, mix Greek yogurt, lemon juice, dill, salt, and pepper until smooth.
Assemble the Bowls: Divide couscous into bowls. Top with turkey meatballs and Greek salad. Drizzle with yogurt sauce if using.