Make the dough. Mix the flour, yeast and salt together in a large bowl. Mix together the sugar and warm water then make a well in the centre of the dry ingredients. Pour the sugar and water into the well. Gradually mix the wet and dry ingredients together and then turn out onto a floured work surface. Knead for 10 minutes. Flour the outside of the ball of dough then place in an oiled bowl. At this stage you can either prove for about 15 minutes somewhere warm or put it into the fridge until you're ready to use.
Preheat the oven to 200° C. Make the sauce. Heat the olive oil over a medium heat. Add the onion, garlic, plenty of salt and 40ml of water. Once the water has evaporated pour in the tin of tomatoes and cook down until it's almost dry. Mix in the tomato puree, chilli powder and oregano and leave to cook a little more until it has a thick consistency. Tip out onto a plate and allow to cool.
Divide the dough into two pieces and roll out until about 5mm thick then place on baking trays. Mix the chicken with the sriracha in a bowl then split between the pizza bases followed by the bacon and mozzarella. Place in the oven and bake for 15 minutes. Drizzle with ranch dressing and serve.