Place the flour, dried yeast, salt, 2 tablespoons of the olive oil into a food processor and pulse for 3 seconds. Pour in most of the water and turn on again, mixing till you have soft dough. Add the remaining water if needed to bind the pizza dough. Turn the dough out onto a floured work surface, and knead the dough till soft for at least 5 minutes. Form into a ball. Grease a large bowl with some of the remaining olive oil and place in the dough. Brush the top with some more oil, cover with cling film, and leave to rise for 45 minutes, or double in size. Turn the dough out onto a floured surface again and knock out the air, flattening the dough. Roll out the dough 1 inch bigger than your baking tray all around. Flour the baking tray, and lift in the dough, pushing into the sides of the tray. Spread over the tomato sauce in a thin layer and lay over the sliced mozzarella. Next, mix together the diced chicken pieces with the barbeque sauce and toss over the pizza. Finish off with the sliced red onion and a good drizzle of olive oil and allow to rise again for 20 minutes. Bake for about 20-25 minutes at 200`c, or until the pizza is golden brown and cooked through.