Lentils with chestnuts and celery

Use the large, greeny-brown Spanish lentils that, unlike hard little lentilles de Puy, are guaranteed to cook to a soft, floury mush. Chestnuts, a semi-wild crop of great importance to pigs as well as people in medieval times, add a smoky, earthy sweetness to a bean or lentil stew. Either dry your own when the nuts ripen in autumn, or look out for them in Mediterranean delis (they keep for years). Potatoes took the place of the chestnut in the Old World cooking pot – the two are rema