Paris was made for a picnic and my Swedish Frenchman chum Danyel Couet came up with this ‘tuna in a jar’ recipe when working and romancing in the city. We once feasted upon a pot of this with a crusty loaf while sitting by the boating pond in the Jardin des Tuileries, a scene that can’t have changed much in the last hundred years or so. Danyel serves his tuna with home-pickled olives, wine-cooked artichokes and his famous stuffed Cam