- In a large heavy bottomed saucepan, heat the oil 
-  Add the onion and sweat for a few minutes 
- Scatter in the cumin seeds and cook for a further 2 minutes, stirring occasionally 
-  Add the garlic, celery and carrots 
-  Sweat for a couple of minutes 
- Pour in the stock 
-  Stir in the tomato purée and coriander 
-  Next add the lentils 
- Stir, bring to the boil and then simmer gently for 30 minutes 
-  Place in a blender or use a stick blender to create a smooth soup 
-  Re heat and season with salt and black pepper to taste 
- Serve with crusty bread