1. Place flours, sugar and cocoa in a food processor. Process until combined. Add butter. Process until mixture resembles breadcrumbs. With motor running, add egg and about 1 1/2 tablespoons iced water. Process until dough comes together. Turn onto a lightly floured surface. Knead dough until smooth. Shape into 4 discs. Wrap in plastic wrap. Refrigerate for 30 minutes.
2. Preheat oven to 180°C/160°C fan-forced. Line two large trays with baking paper. Roll 1 dough disc between 2 sheets of baking paper until 5mm thick. Using template, cut 9 thong shapes (if dough becomes too soft, refrigerate until firm). Place thongs 2cm apart on prepared trays. Repeat with remaining dough discs to make a total of 36 thongs. Freeze for 5 minutes or until firm. Bake for 8 minutes. Stand on trays for 5 minutes. Transfer to a wire rack to cool completely.
3. Make Royal Icing: Lightly whisk egg white and lemon juice together in a bowl. Gradually add icing sugar, whisking until smooth and combined. Tint icing pink (cover icing with damp paper towel to prevent drying out).
4. Cut blue strips from multicoloured sour straps. Discard remaining colours from straps. Cut each blue strip in half lengthways. Cut each strip crossways into 4cm lengths. Spread biscuits with icing. Position 2 blue strips on each biscuit to form thong straps. Top each with a flower. Stand biscuits for 30 minutes or until set. Serve.

For more information visit:

http://www.taste.com.au/recipes/32713/thong+biscuits