Mix in enough of the additional flour to make a soft dough, easy to handle (I use my hands). Turn dough onto a lightly floured surface, and knead until it is smooth and elastic about 6 minutes. Place upside down in a greased bowl, then, turn the dough right side up again, and cover the bowl with a clean towel, paper towels or clear wrap-don't wrap tightly! Let rise in a warm place, free of drafts, until double in size. About 90 minutes.