Step 1 To make meatballs: Put sourdough breadcrumbs in a medium bowl. Add skim milk; leave to soak for 3 minutes. Combine breadcrumb mixture with beef mince, grated zucchini and chopped parsley in a large bowl; season with cracked black pepper. Wet hands to roll tablespoons of mixture into balls.
Step 2 To make tomato–eggplant sauce: Spray a large saucepan with olive oil; set over medium heat. Add onion; cook, stirring occasionally, for 5 minutes, or until soft. Add eggplant to pan; cook, stirring occasionally, for 3–4 minutes, or until golden. Add garlic to pan; cook, stirring for 1 minute, or until mixture is fragrant.
Step 3 Add tomato paste to saucepan; cook for 1 minute, then add diced tomatoes with 1 cup water. Bring mixture to the boil; reduce heat and simmer for 10 minutes. Put half of the tomato–eggplant sauce in an airtight container and place in fridge or freezer (reserving for Sunday’s Chicken, eggplant and capsicum bake with cauliflower mash recipe, see Tips).
Step 4 Meanwhile, set a large non-stick frying pan over medium–high heat and spray with oil. Add meatballs in batches and cook, turning, for 6–8 minutes, or until browned all over and cooked. Remove half of the meatballs from pan (reserving for Saturday’s Spiced pilaf with meatballs, currants and baby spinach recipe, see Tips).
Step 5 Add remaining sauce to pan; simmer for another 2–3 minutes.
Step 6 Divide cooked couscous among serving plates, top with meatballs in sauce and serve with steamed green beans and broccoli.