Prepare the dough. Put the flour in a bowl and make a well in the centre. Add the egg, salt, yeast and enough warm water to make a firm but not too sticky dough. Knead until the dough is completely smooth.
Roll into a large ball, cover with a floured tea towel, and leave for 1 hour in a warm place.
Meanwhile, fry the bacon and onions in the butter and oil until the onions are tr