Cook ½ kg (1 lb 2 oz) of brown lentils, unsoaked, in slightly salted water with a knob of fresh butter, until they are tender but not broken (in earthenware, if possible). Then pass them through a sieve.
Chop finely a small onion, some parsley, sedano (celery grown as a herb) and a carrot. Put this battuto in a pan with 50 g (2 oz) of butter, brown the aromatics, then add a ladleful of stock, or liquor from cooking a cotechino, skimmed of its surface fat. Simmer for 10 minutes. Use this to flavour the lentil purée, which should remain stiff. I sometimes add the juice of half a lemon.
One of the best things to serve with the above-mentioned cotechino, but also with a zampone, a pigeon, pheasant or partridge.