Whole grain rolls

I love whole grain bread but I wasn't able to find anything like that in Hong Kong. So I started investigations how to bake my own bread and I came across a way of producing sourdough just from flour and water. Jamie Oliver provided the details in one of his books.
Mix 500 g of flour (e.g. whole wheat) with enough water so that the resulting dough is quite liquid. Leave the dough outside (on your balcony etc.) so that it can interact with some fresh air for 1 h. Afterwards get it back inside and cover it with cling wrap. Leave it at ambient temperature for the next few days. It will start to form bubbles and get a greyish colour. That's alright. Every second day you should add a hand full of flour and some water. On the fith day the dough should have the colour of beer and smell of yeast. Now you can add 1 kg of flour and as much water to give a nice strong dough. Keep 500 g of the whole dough for the next time. From the rest you can make your bread. Add salt (don't add the salt to the part that you want to keep for the next time) and cereals as you like. Let the dough rest over night so that it can rise nicely, you can cover it with a wet towel to prevent it from getting too dry. On the next morning you can bake the bread. A bread loaf will take about 1 h baking time, rolls only 25 min.
If you use whole grain flour and aditional seeds you will get very nice dark bread. My favourites are sunflower seeds or walnuts.