Step 1 Spray a large non-stick frying pan with cooking oil and set over medium heat. Add onion and cook, stirring occasionally, for 2–3 minutes. Add zucchini and cook, stirring, for 3 more minutes, or until vegies are soft. Transfer to a large bowl; set aside to cool.
Step 2 Add beef mince, breadcrumbs, egg, mustard, sun-dried tomato, basil and pine nuts to vegetables. Mix beef mixture by hand until well combined, then season with cracked black pepper. Divide mixture into 12 equal portions (about ¼ cup each) and roll into balls, then flatten slightly. Place meatballs on a baking tray, cover with plastic wrap and refrigerate for 30 minutes to chill.
Step 3 Spray a large non-stick frying pan with cooking oil and set over medium–high heat. Add meatballs to pan and cook for 3–4 minutes per side, or until golden brown and cooked through. Add passata and simmer for 5 minutes.
Step 4 Divide spaghetti among serving bowls; top with meatballs and parmesan and serve with greens.