In a large bowl, combine 3 cups flour, granulated sugar, salt, pepper and baking powder. Rub the butter into the flour mixture using your fingers or a pastry blender until the butter resembles pea-sized clumps distributed through the flour.

In a small bowl, whisk together the egg and buttermilk. Stir the wet ingredients into the dry ingredients to create a shaggy dough. Fold in the tomatoes, arugula and feta. The dough will be crumbly, but pat it into a rectangle about 1-inch thick on a flour-dusted sheet pan. Cover with plastic wrap and chill the dough in the refrigerator for 30 minutes.

Preheat the oven to 400 degrees F.

Use a 3-inch round cookie cutter to cut out the biscuits. Pat the scraps back together and cut again. Transfer the scones to the prepared sheet pan placing them 2 inches apart.

Brush the tops of the biscuits with buttermilk. Bake for 20-25 minutes until they are golden brown. Cool on a wire rack.

Biscuits are best eaten the day they are baked. Store in an airtight container and refresh in a 300 degree F oven for 5 minutes.