Mix the flour, salt, sugar and yeast in a bowl. Add the water and oil, mix and knead to form a soft, smooth dough. Cover and leave to rise at room temperature for approx. 1 hr. until doubled in size.
To shape and bake
Shape the dough into 20 balls, flatten and transfer to a baking tray lined with baking paper, cover and leave to rise for a further 30 mins. Brush the buns with oil, sprinkle the sesame seeds on top. Bake for approx. 15 mins. in the lower half of an oven preheated to 220°C. Remove from the oven, leave to cool on a cooling rack.
Place the meat and bacon in a bowl, season, mix well by hand until the ingredients have combined to form a compact mass. With wet hands, shape the mixture into 20 burgers. Heat the oil in a non-stick frying pan. Brown the burgers in batches for approx. 2 mins., turn over and top with the cheese, cook for a further 2 mins.
Cut open the buns, spread a little ketchup on the bottom half of each bun. Add the burgers and cover with the top half of each bun, press down gently.