Dissolve yeast in 1/2 cup warm water with 1 tsp. sugar. Allow to sit for 5 minutes until foamy.
Mix together in a large bowl, combine egg, salt, oil, 1/2 c. sugar, milk, sourdough starter and 2 cups flour. Mix well, then add the yeast mixture.
Add another 3 c. flour or more as needed. Knead lightly for about 5 minutes. Cover with a towel and let rise to top of bowl, about 2-3 hours. Shape into 2 loaves or 24 rolls and place in greased pans. Let rise again, about 1-2 hours. Bake at 350 for 30 minutes.

—

To make sourdough starter:
Place milk in a glass jar and let sit at room temperature for 24 hours. Add flour and leave in a warm place for 2-5 days until full of bubbles and sour. To speed the process, you can dissolve yeast in the milk, then add the flour and 1-3 tsp. sugar. Once the starter is nice and bubbly, it is ready to use. To store, keep in a covered glass or plastic container in the fridge with room for it to expand. Don’t use a metal container or lid for storage. After you remove what you need for your recipe, you’ll need to feed your starter with a mix of 1 cup flour and 1 cup water or milk. Mix well into your starter and place it back in the fridge. Stir or use every week or so.