In a medium bowl, whisk together the flours and salt. Add the butter and rub together to incorporate. Mix the water and hibiscus syrup and drizzle in. Knead until it's all a homogenous dough. Do not over-knead. Let rest for 10 minutes.
Using two piece of parchment, roll rested dough into a circle, a little less than 1/4 of an inch thick. Place blueberries and hibiscus petals in the center of the rolled out dough and squeeze a little lemon over the berries.
Fold the edges of the dough into the berries, doing this all around. Brush the edges with butter and sprinkle with sugar. Bake for 30 minutes until crust is golden brown. Serve warm with your favorite cheese!