Measure the milk into a jug, stir in the vinegar, cover and leave for 30 minutes.
Scatter some flour on a large baking tray and pre-heat the oven.
Put the flour, sugar, bicarbonate of soda and salt into a bowl, stir to combine then sieve it all into a mixing bowl.
Pour the prepared milk into the bowl and stir to make a slightly sticky dough.
Tip the dough onto the prepared baking tray and sprinkle a little flour on top and use your hands to mould it into a football or rugby ball shape.
Bake for 40-45 minutes.
Allow to cool completely before slicing.
