Combine milk, water, and oil; bring to a boil. Cool to lukewarm. Dissolve yeast in 1/4 cup warm water; add with sugar and salt to cooled mixture. Stir liquid into flour just enough to blend thoroughly. Cover loosely; let stand in warm place 12 to 18 hours to sour.
Remaining starter can be stored covered in refrigerator for several days or freeze 2 tbs portion quickly on greased baking sheet, then package in moisture-vapor proof container to be used as needed. Bring to room temperature before using.
Combine ingredients in large glass mixing bowl. Mix together until well blended. Let stand uncovered in warm place (80-85F) for 24-48 hours; Stir occasionally. Stir well before use. Pour out required amount and replenish remaining starter by mixing in 1 cup each flour and warm water, Let stand uncovered in a warm place a few hours until it bubbles again before covering loosely and refrigerating. May also be stored in freezer. Use and replenish every two weeks.
Cajun Country -- New Iberia, Louisiana