Line a small loaf tin with baking paper, this is a wet dough and is prone to sticking!
Weigh the flours, salt and toasted caraway seeds if using, into a big bowl. Dissolve the yeast into the water, to make it easier to mix into the dough, and then add the water and the starter to the dry ingredients. Mix with a wooden spoon, (not knead) until there are no dry bits or lumps.
The yeast is an optional extra that speeds things up. Leave it out and the loaf could be left overnight to rise.
With a wet hand, shape the dough and place it into the lined tin. Sprinkle the top with flour and leave to rise in a warm place, until it’s just crowning the tin. The flour on the top will crack as the dough rises giving the loaf its characteristic finish.
Bake HOT at 240ºC with lots of steam (tray with water and rocks in would be great). Then after 15 minutes let the steam out and turn the heat down to 200ºC and continue baking for about 20 minutes.
If you can, leave for 24 hours before cutting and eating.