In a large glass or plastic container, dissolve the yeast in warm water. Stir in the flour and sugar, mix until smooth. (DO NOT USE A METAL SPOON!) Cover loosely and store in a warm place overnight.
The next day, stir and refrigerate.
Stir once each day for the next four days.
On the 5th 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 10th day feed again with 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 15th 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 a day for four days, stir and feed on the fifth day, ready for use on the tenth day.)