There's a simple reason this tangy bread is famous – it's delicious!
Step 1: Make the starter Make the sourdough starter by stirring 2 tablespoons of active dry yeast, 1/2 tablespoon of sugar, and the all-purpose flour into 2 cups of warm water. Cover with plastic wrap and let it rest at room temperature for two days.
Step 2: Combine ingredients In a large bowl, combine 1 cup of bread flour, the remaining sugar, the salt, and the package of yeast. Stir in the milk and butter; then stir in 1 1/2 cups of your starter.
Step 3: Mix in flour Mix in the remaining bread flour gradually. Add more if the dough is too sticky.
Step 4: Knead the dough Turn the dough onto a floured board and knead it for 10 minutes.
TIP: You can also knead the dough in a stand mixer or bread machine.
Step 5: Let rise Place the dough in a lightly oiled bowl, turning the dough around a few times to coat. Cover with a dishcloth or plastic wrap and let it rise until it doubles in volume, one to two hours.
Step 6: Punch down Punch down the dough and then let it rest for 15 minutes before shaping it into two loaves. Place them on a greased baking sheet dusted with coarsely ground cornmeal and let rise until it doubles again, about another hour.
Step 7: Bake Preheat oven to 375 degrees Fahrenheit. Just before you're ready to put in the loaves, gently make 1/4-inch-deep slashes on the top with a sharp knife. If it's a round loaf, make two horizontal and two vertical slashes in a tic-tac-toe pattern. For an oblong loaf, make a few horizontal slits or one long vertical one.
TIP: Dipping the knife in cold water before each slash keeps the dough from sticking to it.
Step 8: Make egg wash Beat an egg with one tablespoon of water and gently brush it over the top of the loaves. Bake until golden brown, about 30 minutes.
FACT: The Ancient Egyptians made sourdough bread as early as 1500 BC.