Thoroughly dissolve yeast in warm water in a large glass or plastic container until foamy, about 5 minutes. Gradually stir 2 cups flour and 1/4 cup sugar into yeast mixture in the container until smooth, about 2 minutes. (Do not use aluminum utensils). Cover loosely and store in a warm place overnight.

The next day, gently stir starter in the container until well combined, about 1 minute. Refrigerate.

Stir once each day for the next four days. On the fifth day, stir, then divide in half. Give half away with feeding instructions.

Feed starter with 1/2 cup white sugar, 1 cup flour, and 1 cup milk. Stir until smooth. Cover and place in refrigerator. Stir once each day for next four days.

On the tenth day feed again with remaining 1/2 cup white sugar, 1 cup flour, and 1 cup milk. Return to refrigerator and stir once each day for the next four days.

On the fifteenth day it is ready to be used for baking. Reserve one cup of the starter in the refrigerator and continue to follow the stir and feed cycle: stir once daily for four days, feed on the fifth day, and use on the tenth day.