Preheat the oven to 180°C and line one or two baking trays. Combine the flour, sugar and baking powder in a large bowl. Add the beaten egg gradually until the dough comes together but is not too wet. Add the fruit, nuts and lemon zest and mix well.

Divide the dough into three pieces. With wet hands, shape each piece into a log about 3 cm in diameter, place them on the prepared trays and flatten slightly. Bake for 20–30 minutes or until golden. Remove from the oven and let them cool for 10 minutes.

Reduce the oven temperature to 140°C. Slice the logs on a slight angle into slices about 5 mm thick and lay them flat on the trays. Bake for 12 minutes, turn the slices over, then bake for a further 10–15 minutes or until pale golden.

Cool the biscotti on a wire rack and store in an airtight container for up to 10 days.