Arzak in San Sebastian in Spain’s Basque country is one of the world’s best restaurants. Juan Mari Arzak has been joined in the kitchen, for the last five years, by his daughter Elena. They are, he says, highly compatible, he being, in his own words, ‘an old rocker’, and she a heavy-metal aficionado. She is an outstanding chef, and I predict that she will be one of the leadi