Candied orange shortbread petticoat tails

Ingredients

• 230 gm plain flour
• 110 gm rice flour
• 110 gm caster sugar (½ cup)
• 230 gm butter, coarsely chopped
• Finely grated rind of ½ orange
• 30 gm glacé orange, diced
• 1 eggwhite, lightly whisked
• 1 tbsp white sugar