Preheat oven to 220C/200C fan-forced. Line a baking tray with baking paper. Position oven rack in the top half of oven.
Sift flour, sugar and salt into a bowl. Add butter. Using fingertips, rub butter into flour mixture until mixture resembles fine breadcrumbs. Add tomato and basil.
Make a well in centre of mixture. Add buttermilk. Using a flat-bladed knife, stir until a sticky dough forms. Turn out onto a lightly floured surface. Knead gently until just smooth.
Roll dough out to a 20cm square. Cut into 16 squares.
Place scones, just touching, on prepared tray. Brush with buttermilk. Bake for 15 minutes or until golden and hollow when tapped on top. Serve for breakfast.