1. Mix milk sugar and vegetable oil in a pan. Heat gently to dissolve the sugar then leave to cool for 15 minutes.
2. Place 125g plain flour and instant yeast in a mixing bowl. Make a well in the centre and add the above mixture. Stir with a spatula until the mixture comes together to form a thick batter. Cover and let the batter sit for at least 1 hour.
3. Add in the remaining 15g flour baking powder baking soda and salt. Stir until the mixture comes together.
4. Cover and leave to chill in fridge for at least four hours. (Note: dough will be more firm and easier to work with if left to chill in fridge).
5. When ready to make the rolls melt the butter sugar and cinnamon together in a pan.
6. Dust the work surface freely with flour and the top and bottom of dough. Roll out the dough into a rectangular shape. Then roll out as thin as possible. Dust the dough and work surface with flour when necessary.
7. Brush the rolled out dough with melted butter mix. Sprinkle the currants evenly over the surface.
8. Start from the opposite end of the dough roll the dough neatly in a line towards you. Roll as tightly as possible. Dust fingers with flour if the dough feels sticky. Pinch the seams to seal.
9. Cut into 1 inch thick slices and arrange on baking tray greased with a little butter. Place the rolls close together so that they are almost touching.
10. Cover and leave to rise overnight in the fridge. The next morning if rolls have doubled in size bake them right away. Otherwise leave at room temperature until double in size before baking.
11. Bake in preheated oven at 180 C for 20 minutes until golden brown.