Create the start by mixing all 3 ingredients and leaving at room temperature overnight.
Once the starter is ready, add the dough ingredients to a stand mixer and mix until a cohesive dough is created. The dough will be rough, which is what you want.
Cover with plastic wrap and let rise for 3 hours total. After the 1st hour, deflate the dough and turn over. Repeat at the 2 hour mark.
After the dough has risen for 3 hours, turn it out onto a floured work area and shape to a 10" round.
Transfer the dough to a greased baking sheet and let rise overnight, in the refrigerator.
Once ready to bake, remove the dough from the refrigerator and let sit for 30 minutes.
Pre-heat the oven to 425 degree fahrenheit.
Mix 1 egg with 1/4 cup water and whisk until combined. Brush the egg mixture over the top of the bread and sprinkle with sesame seeds.
Bake for 20-25 minutes until the top is golden brown.
Remove the bread from the oven and let cool down before slicing.