One Pot Classic Meatballs With Hidden Veg Napoli Sauce

• 2 brown onion, grated
• 2 slices wholemeal bread, crusts removed
• 500 g lean beef mince
• 2 tbsp extra virgin olive oil
• 1 carrot
• 1 zucchini
• 2 garlic cloves
• 700 g passata
• 1 tsp raw sugar (optional)
• 1 tbsp dried Italian herbs