In a food processor, blend the flour, ground almonds, icing sugar, lime zest, baking powder and salt. Add the butter and pulse until the mixture has a sandy texture. Add the egg and pulse again until the dough is moist but still crumbly. Press the dough evenly along the bottom and up the sides of a 9-inch (23 cm) round, 1-inch (2.5 cm) deep tart pan with removable bottom. Prick the dough with a fork. Refrigerate for 30 minutes.
