Step 1

To make the sourdough starter, place grapes in a medium bowl. Use your hands to crush grapes to release as much juice as possible. Add 2 tablespoons of the flour and stir to combine. Cover with a muslin cloth or clean tea towel and place in a warm area. Set aside, stirring occasionally, for 2-3 days, or until mixture ferments (mixture should develop little bubbles and a subtle sour/yeasty smell).

Step 2

Push the mixture through a sieve into a clean bowl. Use the back of a spoon to push as much juice as possible through the sieve. Discard solids. Add remaining flour and water; stir to form a paste. Cover with plastic wrap and set aside in a warm, draught-free place for 24 hours or until mixture bubbles and rises by a quarter.

Step 3

Combine the flour, bread improver and salt in a large bowl. Make a well in the centre. Add the sourdough starter and warm water and use a spoon to stir until combined. Turn onto a lightly floured surface and knead for 10 minutes or until dough is smooth and elastic. Place in a large bowl and cover with plastic wrap. Set aside in a warm, draught-free place for 1-2 hours or until dough doubles in size.

Step 4

Preheat oven to 200°C. Turn the dough onto a lightly floured surface and divide into 2 even portions. Line an oven tray with baking paper. Knead a dough portion for 1 minute until it returns to its original size. Roll dough out to a 30cm long log, that is about 5cm wide. Place on the lined tray. Repeat with remaining dough. Brush dough portions lightly with water and sprinkle with extra flour. Use a sharp knife to cut slashes, 1cm deep, on the top of each loaf. Cover with a clean tea towel and set aside in a warm, draught-free place for 1 hour to rise.

Step 5

Bake in preheated oven for 10 minutes. Reduce oven temperature to 180°C and bake for a further 15 minutes or until golden brown and the loaf sounds hollow when tapped on the base. Serve warm with butter.