If you don't normally make bread and do not have your own sourdough starter( I know, who would?), local artisanal bakers are normally willing to sell or even give you a little. I know this as being a private chef travelling between countries I cannot bring it with me so I always end up getting some this way! - Just ask
Place 300g of sourdough starter in a bowl.
Add 350g of flour and 400ml of water.
Mix together for a thick wet sponge mixture.
Leave covered of overnight in a warm spot.
Scrape the sponge into the kitchen aid or similar machine fitted with the dough hook.
Add 4 tsp. dried yeast, 400g-500g of flour, 12 grams of salt and 3 tbsp. of activated charcoal powder (available from your local health shop)
Mix at a low speed until the dough comes together. You may need to add some more flour but not too much, just enough to bring the dough together and come away from the side of the bowl.
Once the dough is ready put into a bowl and cover. Leave in a warm place and allow to rise until it has doubled in size.
Put the dough onto a flat surface and cut into pieces that weigh roughly 130g. Roll into balls.
At this point you should make sure that your oven has been turned on to 190°C.
Now you can flatten these balls onto a greased tray allowing enough space between them to rise. Spray with water and cover. Leave again to rise until doubled in size.
Once they have doubled in size you can spray with water again and sprinkle with sesame seeds or poppy seeds.
They are now ready to be baked in the oven; they should take no longer than 15-20 mins depending on your oven.