Mix both flours in a mixing bowl and remove about 1/3 and set aside for the filling.
Combine the larger amount of flour with 200 g margarine, 40 g mango puree and the pear juice and work to a smooth dough. Add a little water if necessary.
Heat the oven to 180°C (160° fan), gas 4. Grease 12 tart or bun tins.
Roll the pastry out thinly on a floured surface and use an 8cm cutter to cut out rounds. Gently push the pastry rounds into the tins and prick several times using a fork.
Mix together the remaining ingredients until smooth. Spoon into the pastry cases.
Bake for about 25 minutes until golden brown. Cool in the tin for 5 minutes, then place on a wire rack to cool completely.
For the icing
Sift the icing sugar into a bowl. Gradually beat in the water until smooth. Drizzle over the tarts and leave to set.