Combine the water, yeast, sugar and 2 tablespoons of oil in a jug, mix well. Cover and set aside in a warm place for 5 minutes or until bubbles form on top.
Place the flour and salt in a bowl. Make a well in the centre and pour in yeast mixture. Stir until dough comes together in the bowl. Turn onto a lightly floured surface and knead for 10 minutes or until smooth and elastic. Brush a bowl with oil to grease. Place dough in bowl and cover with plastic wrap and a tea towel. Set aside in a warm, draught-free place for 30 minutes or until dough doubles in size.
Preheat oven to 200°C fan forced. Grease a 20 x 30cm roasting pan or tray. Punch down centre of the dough with your fist. Turn onto a lightly floured surface and knead until smooth. Press into the prepared pan. Cover with a damp tea towel and set aside in a warm, draught-free place for 15 minutes or until doubled in height.
Use your finger to press dimples into the dough. Press the tomatoes into the dough. Scatter over the basil, brush with remaining oil. Bake for 25-30 minutes or until golden and focaccia sounds hollow when tapped on base. Serve warm with buffalo mozzarella and olive oil.