Begin by making the dough. Add the flour and salt to the bowl of a stand mixer fitted with a paddle attachment and mix on a low speed to combine. Add the butter and mix on a low speed until the butter is roughly the size of walnuts.
Combine the brown rice syrup, egg yolk and cream in a small bowl and mix to combine. With the mixer on low slowly drizzle in the egg yolk mixture until incorporated.
Remove the dough from the bowl and place on a lightly floured bench. Don't worry, it will be very shaggy in appearance, and use the palm of your hand to push the dough forward and flatten it. Finally form into a disc and wrap in cling film and refrigerate for at least 1 hour.
Combine the strawberries in a bowl with 2 tbs of brown rice syrup and set aside. In a separate bowl combine the mascarpone, lemon zest and remaining brown rice syrup. Mix to combine before adding the egg.
Preheat the oven to 180 degrees celsius (350 Fahrenheit). Remove the pastry from the refrigerator and place on some lightly floured baking paper. Roll into a circle approximately 30cm in diameter. Slide the pastry onto a baking tray and spread the mascarpone mixture in the center of the dough, leaving a border of about 6cm. Top the mascarpone mixture with the strawberries. Fold the edges of the dough towards the center.
Bake for 35 to 40 minutes, or until golden. Leave to cool for 10 minutes before serving.
If you don't have or would prefer not to use the Brown Rice Syrup feel free to substitute in honey or caster sugar.