Reduce the heat to low, add the remaining oil and stir in the onion, carrot and celery with a pinch of salt. Cook for 8-10 mins until soft, then stir in the garlic, bay leaves, tomato purée, drained lentils, white wine, stock, oregano and parmesan rind, if using. Bring to a boil then return the sausages and fennel to the pan. Cover and simmer for 30 mins until the fennel and veg are tender. Season to taste and scatter over the parsley and parmesan, if using, to serve. Leave to cool before portioning into containers to store in the fridge or freezer bags to lay flat in the freezer. Defrost overnight in the fridge, then reheat in a saucepan on the hob until piping hot.
