Celeriac, potato and hazelnut soup with sautéed leeks

This is a fine autumn or winter soup, comforting and with a surprising degree of sweetness. Bridget thinks it tastes of apples. It was inspired by a lunch I wasn’t even at, in Ballymaloe in East Cork. Celeriac and hazelnut soup was served and devoured, and, later, while the telling of the lunch was going on I was thinking what a brilliant combination that was. An hour later we had produced a version. I still haven’t tasted the original; I don’t get out enough. The weight of celeriac here, a