Tip the onion, celery and carrots into
a large non-stick saucepan and add
2-3 tbsp water or stock, if you have
some. Cook gently, stirring often, until
the vegetables are soft.
Add the garlic, tomato purée and
balsamic vinegar, cook on a high heat for
1 min more, add the diced veg, lentils,
tomatoes, then bring up to the boil.
Turn to a simmer, then cook for about
20 mins. Meanwhile, cook the pasta
following pack instructions, then drain.
Season the ragu and serve with pasta
and Parmesan on top, if you like.