Prepare the biscuit dough by sifting together the flour, baking soda, salt and sugar. Cut the butter into the flour using a pastry cutter, until it resembles pea sized pieces. Combine the vanilla with the buttermilk and add it to the sifted dry ingredients, mixing until just combined. Set aside to be used later.
Place the fruit in a large bowl, add lemon juice and zest, sugar, and corn starch, tossing to coat. Spread the fruit evenly across the bottom of an oven safe baking dish.
Gabbing a handful of prepared dough at a time, press the dough 1/4 -inch thick between your hands, then place it on top of the fruit in the baking dish.
Brush the top of the biscuits lightly with buttermilk and sprinkle with raw sugar. Bake in the preheated oven for 35-40 minutes, or until the biscuits are golden brown. Let cool slightly and set before serving. Garnish with fresh mint and optionally serve with frozen vanilla custard.
Notes
Garnish with fresh mint and optionally serve with frozen vanilla custard.