Lentil soup is one of my favourites - warm, comforting, tasty and really easy to make
Peel and finely chop the onion, celery and carrot into 5mm (quarter inch) cubes. Melt the butter in a large saucepan on low heat. Stir in the onion and get it completely coated in butter. Let it cook for a few minutes, then stir in the carrot and celery.
Rinse the lentils in water and pick out any stones. Stir them into the vegetables, generously cover with water and bring to the boil. Cut the bacon into small pieces and add it to the soup along with the bay leaf and smoked paprika.
When the soup is boiling turn down the heat, put a lid on the pan and simmer for 30 minutes. Test the lentils to see if they are cooked - if not, continue cooking until they are - possibly another 30-45 minutes depending on the age of the lentils and the texture you want. I like my lentils to be a bit like mush, so I cook the soup for longer.
You can eat the soup immediately, or leave it for a day or two - the flavour will improve.