Soften the onions over a medium heat with some butter.
Add tomatoes and bring to the boil
Add lentils and stir in. And add the balsamic vinegar
Cover and leave to simmer for 30-35 minutes stirring occasionally
Add water if needed, the lentils soak a lot of the liquid up... Add the stock cube and seasoning to taste. I like it really peppery it gives it a good kick!
Right at the end add the chopped fresh basil and stir through.
What I love about making soup is there is no hard and fast rules. I also added some celery to this one. If you have other veg spare just throw it in! Enjoy.
Enjoy with a slice of crusty bread!