- Soak all the lentils together in lots of cold water overnight. Drain well and set aside.
- In a saucepan melt the butter and olive oil together. Add the bacon and cook for 5 minutes then add the onions garlic and celery. Cover and sweat until soft but not coloured on a gentle heat. Then add the carrots and cook for another 5 minutes. Season with salt, pepper and sugar.
- Add the lentils, tomatoes, paprika, chilli, bay and mustard along with the stock.
- Increase the heat and simmer until the lentils are tender.
- Pulse with a stick blender a couple of times to break up the veg a little bit. Do not blend smooth.
- Add a bit more stock if neccessary at this stage.
- Add the spinach and lemon and adjust seasoning.