You dreamed it, therefore it exists...
To make a sourdough starter, mix 1 C. flour and 3/4 C. water together, put in a glass container or ceramic bow, and let sit for a week. It will get bubbly and get hooch on the top. You can mix it back in. There are much more complicated ways to make it but this one is the easiest and works for me.
Most recently, during a cob workshop, the vegan sourdough I made was:
Start the starter the night before: 2T starter, 1 C. flour, 3/4 C. water.
In the morning, remove 2T starter for next time.
To what is left in the bowl, add a couple cups of water, a drizzle of olive oil (1/4 C ?), a drizzle (1/4 C.?) of aquave, and about 2 teaspoons salt. Mix in a couple cups of flour or enough for the consistency of pancake batter. Let sit until bubbly again or, with out the sponge rise, add more flour to make a dough. Knead until smooth.
Let rise until double.
Shape.
Let rise until almost double. When close, preheat oven to 425 degrees. Once the oven is preheated, reduce heat to 325 degrees and bake loaves until done, about 45 to 60 minutes dependent on the size of your loaves.
Let cool at least 20 minutes before cutting if at all possible because the bread is still baking as it is cool. This is something that does not happen often in our house.
I have had lovely success with whole wheat but I like fresh ground best. If you are going to add flax, add ground flax seeds. Oat meal works well and adds lovely texture if it is precooked and cooled. Mashed potatoes add egg like consistency, similar to oats.
I find bread baking is much cheaper then bread buying.
Two cookbooks to consider:
Laurel Kitchen's Bread Book by Laurel Roberston and others
The Tassarja Bread Book by Edward Espe Brown
Bread is very forgiving so do not be intimidated. Get in there and go for it. And I promise, your "mistakes" will get eaten, if only when they are 20 minutes out of the oven!
Have fun!
