6 cups unbleached all-purpose flour
2 teaspoons salt
1-1/2 tablespoons dry yeast
2 cups warm water
2 eggs
1/4 cup olive oil
4 medium-sized onions
2 tablespoons dried oregano
Extra virgin olive oil for cooking and drizzling
Peel and slice the onions in half from top to bottom and then slice them into 1/4 inch thick half-rings. Place the onions in a saute pan with 2 tablespoons olive oil over moderate heat and cook for about 10 minutes until translucent and lightly golden in color, then set aside.
Heat the water to 100° F then pour into a medium-sized bowl and stir in the yeast. Let the yeast dissolve until it foams, about 15 minutes. Combine the flour in a large mixing bowl with the salt and make a well in the center. Add the yeast, egg and olive oil to the well and work the dough into a ball. Turn out the dough onto a flour-dusted work surface and knead the dough for about 10 to 15 minutes until it is smooth and elastic.
Brush a 12 X 18-inch baking sheet with olive oil. Punch down the dough and shape or roll it to fit the pan. Transfer the dough to the pan and fit it to the edges of the pan. Brush the surface of the dough with olive oil and sprinkle the dried oregano over it. Spread the cooked onions over the top and gently press them into the surface. Salt to taste if desired, and drizzle with olive oil. Cover the pan with a kitchen towel and allow the dough to rise for about 45 minutes to an hour.
Preheat the oven to 400° F and bake the sfincione for 35 to 40 minutes or until the bottom of the crust is golden brown.
Slice into 8 square pieces with a knife or pizza cutter and serve.