1. In a large saucepan sweat the onion, garlic, leeks, celery and carrot in the vegetable oil until softened.
2. Add the chopped tomatoes and passata and cook together for a few minutes. Puree until smooth.
3. Gently stir the tomato and basil seasoning through the oat balls and allow to marinate.
4. Mix into the sauce and cook gently for 5 minutes.
5. Add the gnocchi and simmer for 1 hour.
6. Serve garnished with fresh torn basil leaves and black pepper.