Sprinkle yeast over warm water in a large glass or ceramic mixing bowl and allow yeast to bloom about 5 minutes.

Stir in buttermilk, sugar and 1 ½ cups of flour. Cover loosely with a kitchen towel and allow mixture to stand in a warm place for 24 hours.

Whisk in the remaining ¼ cup of flour and allow to stand loosely covered another 24 hours in a warm place.

If you are using immediately, test to ensure it is ready by dropping a teaspoon of the starter in a glass of water. It should float. If it doesn't float feed it ½ cup each of flour and water and allow to stand another 4 hours or more until it floats. Ensure that you keep 2-3 Tablespoons of the starter so you can feed and maintain it ongoing.

To Store/Maintain: Refrigerate starter in an airtight container. On a weekly basis discard half the starter, add ½ cup of water and ½ cup of flour to the remaining starter. Stir well and return to the fridge.

To Use Starter From the Fridge- Discard all but about ½ cup of the starter. Feed it ½ cup of water and ½ cup of flour and leave it, uncovered, at room temperature or somewhere warm for about 4 hours. This can take more of less time depending on the temperature and strength of your starter. (Alternatively you can put it out on the counter, uncovered, the day before and feed it two times about 12 hours apart.)

Test your starter before using. Do NOT skip this step because it takes time and effort to make a good sourdough and if your starter is not ready your work will be for nothing. Take a teaspoon of the starter and drop it in a glass of water. If it floats it is ready. If it doesn't it needs more time.

Sourdough recipes will tell how much starter to use. When you use some starter, replenish the remainder of the starter with equal parts flour and water and store air tight in the fridge.