1. Heat the oil in a pan and add onion and cook over a low heat for 3-4 minutes, until soft. Season with sea salt and freshly ground black pepper and stir through the chilli flakes.
2. Stir in the garlic and cook for a few seconds then stir through the lentils so they are all coated, then add the tomato puree and Canderel and stir.
3. Now tip in the canned tomatoes and stock and bring to the boil. Then reduce to a simmer and cook gently for about 25-30 minutes until the lentils are soft. If you need to top up with any more hot water, do so a little at a time.
4. Taste and season again if needed. Blend if you wish, but there is no need. Ladle into bowls and serve with a garnish of fresh parsley.