Preheat oven to 400 degrees F (200 degrees C).
To make the biscuits, mix the All-Purpose Flour (100 gram), Unsalted Butter (5 tablespoon), Caster Sugar (100 gram), zest of the Lemon (1), and Egg (2) together in a bowl or food processor until a soft ball of dough has formed.
Rest in the refrigerator for 30 minutes. Roll out thinly between to layers of baking paper to prevent sticking.
Cut out 8 biscuits with a 7 to 8-cm (2 3/4 to 3 1/2-inch) pastry cutter and bake in the oven for 6-8 minutes. Leave to cool completely.
Take the remaining Fresh Strawberry (150 gram) and pureé in a blender with Powdered Confectioners Sugar (50 gram) and Lemon Juice (1 teaspoon). Pass through a fine sieve and chill the mixture until required.
For the syllabub, combine the Caster Sugar (50 gram), zest and juice of the Lemon (1), the zest and juice of the Orange (1), and mix with the Heavy Cream (300 milliliter). Whisk until it forms soft peaks. Chill until required.
To serve, set down some syllabub on the plate and place down one biscuit (this will help stabilize the base). Pipe or spoon a few spoonfuls of the syllabub in the center of the biscuit and surround with the Fresh Strawberry (250 gram) to make pillars. Fill with more cream and top with another biscuit. Dust with Powdered Confectioners Sugar (to taste), spoon over the coulis around the plate and garnish with Fresh Mint Leaves (to taste). Serve immediately.