Caroline and Robin Weir published their first book on ice cream 12 years ago and it was regarded by home cooks and professional chefs as a bible. They have now brought out their second major publication Ice creams, Sorbets & Gelati — The Definitive Guide (Grub Street Press, £25) which builds on the framework of the first book, and embraces recent research and new recipes. This recipe, which works as well for gin as for vodka, comes from this superb new book.

YOU WILL NEED 8 tbspns vodka 500ml (16 fl oz) sugar syrup. This is made by boiling 1pt (1/2 litre) water to which you add half a kilo (12oz) sugar, then stir over moderate heat until sugar has dissolved. Cool and use as required 375 ml (12 fl oz) tonic water Juice of one lemon — strained.