1. First make the meatballs: Preheat oven to 200°C/180°C fan/gas 6.
2. Add the mince, breadcrumbs, 1 tbsp tomato purée, egg yolk, fresh basil, stock cube (crushed), and salt and pepper into a large bowl. Use your hands to combine all ingredients really well. Roll into 20 even-sized balls, each about the size of a ping pong ball.
3. Add 2 tbsp olive oil and 25g butter to a frying pan on medium-high heat, cook meatballs in batches of 8-10 ensuring they are browned all over. Set aside.
4. In the same frying pan add 2 tbsp olive oil and 25g butter to a frying pan on medium-high heat and brown off the onion for 2-3 minutes.
5. Add crushed garlic and fry for a further 1 minute, then add the red pepper and tomatoes.
6. Add your tin of chopped tomatoes, stir, and bring to a simmer. Allow to reduce to a sauce consistency.
7. Use a handheld blender to blitz the vegetables into a smooth sauce.
8. Return the meatballs to the tomato sauce, and add a little water if required to bring the sauce just below the height of the meatballs. Simmer for 30 minutes until the meatballs are cooked through.
9. For a slow-cook option: Transfer everything to a slow cooker and cook on low for 3-4 hours.
10. Garnish with grated parmesan before serving with pasta or potatoes.

Sustainable Tip: Reduce food waste and freeze any leftovers to use on a day when you may not have time to cook dinner.