1. Rinse the lentils in sieve under cold running water, then place in a pan with 600ml of water. Add a pinch of salt, bring to the boil, then reduce the heat and simmer for 15-20 minutes or until ‘al dente’- just tender but still with a little bite. Drain in a sieve and spread out on a tray to dry if not using immediately.
2. To make the caramelised onions, melt the butter in a frying pan and cook them very slowly until golden brown and caramelised. Season to taste.
3. Heat a frying pan over a medium heat. Add one tablespoon of the rapeseed oil to the pan, then add the sausages and sauté over a medium heat for about 10 minutes until cooked through and nicely browned, turning regularly.
4. Meanwhile, heat the remaining oil in a pan and sweat the leek, carrots and celery for about 10 minutes until softened but not coloured. Stir the smoked paprika, cumin and cinnamon and cook for another minute or so. Fold in the cooked lentils and then pour in the chicken stock. Season to taste and simmer for a few minutes until you have a loose sauce and the vegetables are completely tender.
5. Finally stir in the parsley. Spoon the spiced lentil stew into warmed wide rimmed bowls and put a pile of the caramelised onions in the middle of each one. Add a spoonful of the crème fraîche and arrange the pork sausages on top to serve.