Pour yeast/water mixture into bowl containing 5 cups flour. Stir.
Spread out parchment paper, and sprinkle with flour. Transfer dough from mixing bowl onto parchment paper. Knead. Repeatedly add more flour until dough feels fairly dry and consistent.
Sprinkle bowl with flour. Roll dough into a ball, sprinkle outside with flour, and put into bowl.
Cover bowl with a towel. Let stand for 2 hours to rise.