Step 1

In a bowl, mix all the starter ingredients until well combined. Scoop the mixture into a clean jar covered with a loose lid and leave it to double overnight.

Step 2

Mix the flour, sugar, and salt in a large bowl. Add to this the water, milk, and sourdough starter and mix into a shaggy dough.

Step 3

Tip this dough onto a workbench and use a slap and fold kneading method to bring the dough together. It will be sticky but kneading it will give it strength. Knead it for 5 minutes. Slap the dough down, and fold it over. Repeat this movement quickly.

Step 4

Add in the cubed butter, a few cubes at a time, and knead them in. The butter is going to make it extra sticky but the dough will have some strength already from the previous kneading.

Step 5

Continue slap and folding for a further 6-8 minutes. The dough won't be smooth yet but should feel much stronger.

Step 6

Add the dough to a bowl and let it bulk ferment in a warm spot (ideally around 25°C/77°F) for 3-4 hours. Perform 3-4 sets of stretch and folds during this fermenting time, one every hour. You can create a warm and humid spot by placing the dough into a turned-off oven alongside a large cup of boiled water. Replace the water as needed when it cools down.

Step 7

The dough should feel lighter and puffier. In a warm spot 3 hours may be enough, but extend the ferment if it's cooler.

Step 8

Optional Overnight cold ferment - At this point, the dough can also be refrigerated overnight, then shaped and risen in the morning.

Step 9

Pull the dough from the bowl onto a floured workbench and cut it into 4 pieces. Roll each piece into a log and cut each log into 4 pieces so there are 16 in total.

Step 10

If you're after really even dinner rolls, weigh the dough first so you can work out how big each piece should be.

Step 11

Shape each piece into a tight ball by bringing all the edges of each dough piece into the middle, then flip it upside down so it's seam-side facing down. Use the palms of your hands to cup the ball and spin it round and round on the bench, creating some surface tension. The dough will be sticky so use the flour you need to to ensure it doesn't stick to you.

Step 12

Place each ball into a lined 9x9"' baking dish

Step 13

Leave the dough balls to bulk out for 3-4 hours in a warm spot (ideally around 25°C/77°F) until doubled in size.

Step 14

You can create a warm and humid spot by placing the dish into a turned-off oven alongside a large cup of boiled water. Replace the water if it cools down.

Step 15

Preheat the oven to 200°C/392°F.

Step 16

Whisk together the egg with the water. Brush the tops of the rolls with egg wash.

Step 17

Bake the rolls for around 25 minutes until puffed and deep brown.

Step 18

After baking, brush the warm dinner roll tops with melted butter.