I have a question about step 5 on the recipe "Cool Rise Challah" from Bria. It says:
"Knead 5 to 10 minutes, adding additional flour as needed, until it is smooth, elastic, and passes the windowpane test. Place the dough in a large, lightly oiled bowl, turning it over once to fully coat with oil. Cover with a tea towel and let raise for 20 minutes on the counter. "
What is the windowpane test? thank you!