by: Max M Rasmussen

Make a Sourdough Starter

Surdej ser sjældent så lækkert ud som det smager. - Max M Rasmussen
Video recipe - It is easy to make your own sourdough. Despite the fact that most people around the world have only heard about this mysterious thing called "homemade bread based on sourdough". The problem is almost always to get started. To make the sourdough. But it is not hard, and it is something we do routinely here in denmark, where most of the bread we eat is sourdough ryebread.

Yeast is a kind of fungus. It is a pure culture. Which means that is consists of only one kind of microorganism. That is what make bread based on yeast similar and predictable. Most of us like yeast bread the most.

But once in a while it is nice to have some bread with a different taste and texture.

Not to speak of us danes belowed "rugbrød" (ryebread). It is dark, heavy, soft, full of grains and very sour. Often it contains no wheat flour at all. Danish ryebread used to be the bread of the poor. A danish polenta if you want. But it is really in the mainstream, and every dane eats it every day for  lunch. Kids and adults alike.

The industrial bread is sort of ok, as ryebread is not as delicate as white bread. But it is a lot better when you make your own.

And it really is easy. The air around us is surrounded by bakterie and spores. So if we let any kind of food stand out in the air it will be invaded by the microorganisms that are suited to exactly that kind of food. We know it from mouldy food and bread.

So if we leave out some wet flour (dough) out on the table, it will be invaded by dough fungi. Simply because those are the one best suited for that kind of food.

There are two schools of sourdough. The dry and the wet method.

The principle behind the dry method is that you knead your sourdough into the the dough you want to bake. And before you add the salt, you take a portion of the dough and put it aside. That portion is then the starter for the next batch of dough you make.

The principle behind the wet method is to have a sourdough that you feed regularly. And then when you need it you just pour yourself a portion and leave some of it back. That reminder you then keep feeding.  The sourdough them becomes a kind of yeast that you can just add to your actual dough. I much prefer the wet method,

I can not count the number of times I have started up a sourdough and mixed it into a dough. Only to forget to put aside a portion of the dough for the next time. Or at least after I have put in the salt. (Sourdough does not like to live in an environment that is too salty.)

The wet method is easy to remember, understand, maintain and take care of. Since I started using the wet method I have only had to start a new sourdough when wild yeast has taken over the old one.


  • Rye flour
  • Wheat flour (can be exluded)
  • Water


Put a 2 dl (or 1 cup) of water and 2 dl (or one cup) of flour into a bowl. I usually use 50/50 course rye flour and white wheat flour.

a 50/50 mixture is good for both traditional danish rye breads and for lighter breads. Normally i mix the flour mixture in a jam jar. That way I do not have to measure every time I need to feed the sourdough.

Then you just leave the bowl outside on the kitchen table, and the yeast and germs will find it themself.

Every morning you then pour in 1 dl (½ cup) of water and 1 dl (½ cup) of flour mixture.

You just keep doing that until it becomes light, and foamy.

A hot summers day next to an open window is the best location. That can produce a sourdogh in as little as 24 hours. Simply because there are more micro-organisms in the air on a hot summer day. In the winter with closed windows it can take as much as a week to get going.

You just keep doing that until it becomes light, and foamy.

You can be unlucky and get some microorganisms that tastes bad. So called wild yeast. So if it smells and tastes badly you must throw it out and start again.

It is ok if it has large bubbles or that it looks funky or gross. That does not matter. As long as it smells like ryebread, sourdough (and that can be hard to explain of you have not had sourdough bread before.). But if it reminds you a bit about beer, that is it. It is also ok if it smells a bit like vinegar.

I have never had a sourdough make me sick, and I have never heard about it.

If you think that the sourdough is taking to long, especially in the winter, you kan kickstart it by putting microorganisms into it.


  • Honey
  • Buttermilk or any other fermented milk product. (I don't know what they are called in different countries. But preferably ones that are fermented at room temperature.)
  • Crushed grape (there is wine yeast on the peel)
  • A little bakers yeast, the size of ½ a pea (or 1/8 tsp of dried yeast)

You can Just throw it all in a mixture and see if it works. There is nothing in there that will make you sick. If you use too much bakers yeast it can take a while until the taste becomes sufficiently sour. Yeast has a tendency to take over the dough.

You must remember that sourdough is not a monoculture

it consists of a lot of microorganisms. They all fight for the power in the dough. So the taste of the dough changes accordingly to how you treat it.

If it is kept in a cold location it is it will be more sour. It there is more rye flour in it, it will be more sour.

You can also swap out the rye flour for spelt flour, and that will give you a sourdough that is less sour and very good for lighter breads.

Remember that you can start a sourdough with a new flour mixture from your existing sourdough. That is a lot faster. About a day.

Maintenance and storage

It is easy to keep a sourdough. Just add 1 dl (½ cup) water and 1 dl (½ cup) flour mixture every day. That way you will have plenty of sourdough next time you need it. If you bake every day you can just add as much as you need.

If you don't need it for a while you can just put it in the fridge. Then it should be feed ever 2 weeks at least.

When you finally have a good sourdough you can get a bit paranoid about losing it to wild yeast. But you can save it for the future.

Just pour something on a sheet of baking paper and let it dry out. When it is completely fry you can scrape of the flakes and save them for later in a jar or a bag. That way you can easily start up a new good sourdough again.

You can also freeze the flakes and save them for months.

Sometimes the sourdough seems to fizzle out. Then you can re-awake it with a little yeast or some fermented milk.

by: acheng

Hello Max,

Is there anyway to make a paleo starter?  Thanks!

Purely Paleo



Not really any that I can think of. The paeleo equivalent is probably fermented vegetables.

by: Anonymous

I couldn't understand at the end of the video, you said you could keep it in the refrigerator,  for how long?



Loved it! Looks easy...

by: Anonymous

Hello, Max. Thank you for sharing your excellent knowledge and experience in these videos and recipes. I've made the "Danish Sour Dough Rye Bread - My Favourite Recipe" with great success. It will become a staple.

As I made the sourdough starter from scratch for that recipe, everything flowed quite naturally. With my sourdough starter coming out of the fridge after a week now, however, it's not clear to me whether it's ready for use in a recipe right away or needs to be fed again prior to use. If you could clear that up, it would be most appreciated.

Thank you again.



by: Anonymous

Great sourdough starter!

Your sourdough starter is very very good. The batch I made a few weeks ago tasted of vinegar; I liked the taste and was glad you mentioned it in your notes. I used to make your rugbrod which was just as I remembered real Danish rugbrod to be. I am now adding to my original batch and will be making more rugbrod soon. Mange tak.
by: Anonymous


The video recipe was exactly what I was looking for - no fuss, no gushing or hand-waving, just straightforward instructions. Now looking at the rest of your site and love it.
by: Anonymous


My soy keeps getting moldy. I've covered it with cheesecloth to keep the big bugs out, but after three or four days, it develops mold. Even when I'm adding fresh flour/water. it doesn't smell bad...it still smells like sour. Should I be worried?
by: Anonymous


No. A light soft mold is actually just yeast growing on top. You just stir that back in. A dark (black/bluish) mold should be removed.
by: Anonymous


That's supposed to be sour, not soy. Sorry, I'm on mobile.
by: Anonymous


Hi is it possible to use only wheat flour ?
by: Anonymous

Amount of flour

Hello! yesterday i started my own starter, but i don't know how much of this i can add to 500 grams of flour for example. It's already smelling nice and a little bubbly. I would be grateful if you could tell me. Thanks a lot :-)