Using a sharp, flexible knife, cut off a 5mm (¼in) sliver from the base and top of the fruit. Starting from the top and following the contour of the fruit, cut off 5 bands of peel, 3cm (1in) wide and 6cm (2in) long, from each fruit (including the pith). Cut each band into 3 strips, each 1cm (½in) wide.
Put the strips in a saucepan, cover with cold water and bri