Combine chopped rhubarb with 300g of the sugar, the juice of the oranges and the ginger plus syrup. Divide between 3 x 6 portion pie dishes or one large tin/dish.
Combine grated rind with remaining sugar and put to one side.
Cut out three lids for dishes and use trimmings to cut strips to form borders for the dish rims. Brush the rims with beaten egg white, press strips onto rim, then top with pastry lids. Trim off excess, knock up and flute edges and make 2-3 slits in the top of the lid.
Brush the top with beaten egg white and sprinkle with the sugar and orange rind mixture, bake for 20 minutes or until the pastry has risen and is golden brown.