Combine flour, yeast, sugar, and salt in a large bowl. Add half of the warm water. Do not stir. Let stand until yeast foams (about 10 minutes). Stir in remaining water, olive oil, snipped sage, dry white wine, and pepper. Turn dough out onto a lightly floured surface. Knead for 3 minutes. Shape dough into a ball. Place in a lightly greased large bowl, turning once to grease the surface. Cover; let rise until doubled (about 50 minutes).
Grease a 12-inch pizza pan. Place the dough on the pan. Use the palms of your hands to pat the dough into an even round just slightly smaller than the pan. Using your fingertips, poke the dough all over to dimple surface. Press the onion slices and sage leaves onto the dough. Cover loosely and let rise for 30 minutes.
Bake in a 400 degree F oven for 25 to 30 minutes or until golden brown. Serve warm or cool. Cut into 12 wedges. Makes 12 wedges.