Desem, or 'dough' starter is one of the easiest ways of making sourdough bread at home. It requires substantially less feeding than a regular liquid starter.
However, to establish a desem is a bit difficult from a young liquid starter - many people tell me that they end up with a chunk of odourless dough which, when they use it, doesn't produce outstanding results. This is often because the fermentation they had to begin with in their liquid starter wasn't yet strong enough to handle the change to the dryer environment of a dry dough starter.
For these people I suggest using an established sourdough culture, or to culture their liquid starter for a bit longer (a month or two) before attempting the desem. From experience, a more cultured starter works better for a desem.
If you have already made a desem or dough, and have experienced less than acceptable results in terms of rise, I suggest ageing it in the fridge for a couple of months before using it again. It'll keep - simply feed it till it's quite solid, put it in a small plastic container with the lid almost snapped closed, and leave it in a cool part of the fridge for a month or two. You'll find that the outside of the chunk is quite mouldy and possibly dry, but the inside will be a very sweet, gooey mass which is extremely sticky. You just cut away the outside part, discard, and feed the gooey mass with flour straight away. Your starter will now make great bread, and will improve with regular use. Simply maintain the starter in a fairly doughy state, and it will be useable any time.
SHORTCUTS TO DOUGH STARTER SUCCESS
If you don't want to go through the quite lengthy process of building a mature sourdough culture, there are some commercially available starters (which are based on a liquid in most cases). I haven't actually seen a commercially or privately available desem starter in Australia except for mine. You can purchase this here.
You may also have a friend who makes sourdough who will no doubt be happy to share some of theirs with you. A well established liquid starter can be made into a desem starter quite easily.
Desem starters like to be used with a preferment, or sourdough sponge, when you are making dough. This is just a way of activating the dry dough starter, and will make all the difference in how high your loaves rise, as it will in the way the starter mixes naturally into water before making a dough, rather than starting with flour.
The size of the starter you keep will affect the flavour of bread you make too. A 300 gram chunk will need a total feed of 100 grams of flour and 50 mls of water to replenish enough for a couple of kilos of dough each time. Thus, the ferment is being completely refreshed every two breadmaking sessions.
By keeping a larger starter, say 500 grams or more, and only refreshing the same amount (150 grams), you will keep the starter a bit more mature, because there is a larger fermenting base. You would think that this might lead to overripening starter over time, but if the starter is maintained in a dough state like this, overripening is not really an issue.
Want some live Desem? Mine is nearly 30 years old, and I sell it through our School of Sourdough sister website. I can send it to you anywhere in Australia.
(Overseas orders are not possible due to various quarantine laws of different countries.)