• In the morning feed your starter so you can use 150g of it once it has risen.
• For this dough it could be 40g starter, 80g flour and 80g water. This will make approximately 200g starter. 150g can be used for the dough and the remaining starter can be fed again 1:2:2 and stored for the next time you need it.
  
• Once the starter has doubled, mix the flour, cornstarch, sugar and salt in a bowl. Add the water, milk and sourdough starter and combine into a shaggy dough.
• Add in the butter cubes and work them into the dough slightly.
• Transfer the dough to the bench and knead it for 10 minutes to both work in the butter and develop the gluten in the dough. It will be a very sticky dough, but don't worry it will come together if you keep kneading.
• Once the dough feels stronger, take a little break. Giving the dough a rest for a couple of minutes and coming back to it with clean damp hands will make it easier.
• Once kneaded, place the dough in a bowl and cover it with a upside down plate to stop it drying out.
• Leave the dough to ferment at room temperature (one that’s between 21-23°C / 69-74°F) for 2 hours before transferring to the fridge overnight.
• Keep the dough refrigerated for a minimum of 8 hours, or up to 20 hours, depending on when you want to bake the dinner rolls.

The Next Day

• Remove the dough from the refrigerator can take it from the bowl. Place it on a lightly floured bench and cut it into 8 even pieces. If you want small rolls, you can the dough into 12 instead.
• Shape each piece into a tight ball and place them in a lined tin. I use a round 23cm cake tin.
• Leave the dough balls to bulk out now for between 2-4 hours, until doubled in size. If your room temperature is cold, you can create a warm spot by lightly preheating and turning off the oven and placing them in there.
• Preheat the oven to 200°C (392°F) fan-bake or 220°C (428°F) regular oven.
• Brush the tops of the buns with milk, then bake them for around 20 minutes until baked through and browned.
• Once baked, brush the tops with melted butter. Leave them to cool slightly before serving.