Dissolve the yeast in the cold water.

Add salt and sourdough and stir until it becomes a homogeneous/consistent mass.

Gradually add the flour and mix with a stand mixer for about 10 minutes.

Mix at medium-high speed until the dough releases from the sides of the bowl. 

Let the dough rise/rest for 6-8 hours under a shower cap at room temperature.

Turn the dough out onto a floured surface and fold it into a long loaf.

Then divide the loaf into small rolls about 3 cm long. 

Place the small rolls on baking paper and let them rise for 30 minutes.

Meanwhile, preheat the oven to 250 degrees Celsius (482 degrees Fahrenheit) with the baking tray inside. This will heat it up along with the oven, which will later help with baking the bread, giving it a crispy bottom.

Carefully remove the hot baking tray from the oven and place the baking paper with the rolls onto the tray.

Return it to the oven and bake the bread at 230 degrees Celsius (446 degrees Fahrenheit) with fan for 8-10 minutes. 

Let the baked rolls cool on a wire rack before serving.