Instructions

1. Finely chop the celery, carrot, onion and garlic.
2. Heat the oil in a pot, then add the chopped vegetables and sauté for 5 minutes.
3. Meanwhile, peel and chop the sweet potatoes.
4. When the veggies have softened, add herbs and tomato purée, then stir for a few seconds.
5. Add the sweet potato pieces, stock cube and tinned tomatoes. Using the tin, add some water to just cover the veggies.
6. Bring to the boil and cook, over low heat, for 20-25 minutes.
7. In another pot cook the pasta, following the instructions on the packet.
8. Using a stick blender, process the stew until you get a thick, silky sauce. Add the fresh herbs and process again.
9. Drain the pasta and mix in with the sauce, then add the mozzarella cheese balls and toss.
10. Serve immediately.