Heat the oil in a large non-stick saucepan. Add the rosemary, thyme, onion, carrot, celery and leek and sweat for 6–7 minutes, covered, over a low heat or until the onions are soft.
Add the garlic, dried chilli (if using), stock and lentils, bring to a boil, then cover and simmer gently until the lentils are cooked, around 25 minutes. Pour about one-third of the soup into a blender, purée to a paste, then stir back into the saucepan along with seasoning, parsley and lemon juice (if using) to taste. Add extra warm water from the kettle if you prefer a thinner consistency, then serve.
Eat Right For Your Body Type by Anjum Anand, published by Quadrille, £14.99