Stir yeast into warm water in a large mixing bowl. Let stand for 10 minutes. Stir in 2 c flour & beat till mixture is sticky. Sprinkle some of the remaining flour on a board & knead in the remaining flour until the dough is smooth & elastic. Place in an oiled bowl, cover & let rise till doubled.
Punch down, fold in 4 tb olive oil & the salt. Knead again till smooth. Roll into a circle 10 to 12 inches in diameter. Place on a well oiled 15 inch pizza pan dusted with cornmeal. Let rise till doubled.
Heat remaining olive oil in a frying pan & gently cook the onion for 8 to 10 minutes. Spread onions over risen dough & sprinkle with pepper. Bake at 425F for 30 minutes.
Paolo Gavin, "Italian Vegetarian Cooking"