Lightly spoon flour into dry measuring cups; level with a knife. Place flour, 1/2 teaspoon salt, and yeast in a food processor; pulse 2 times or until blended. With processor on, slowly add water and 1 tablespoon oil through food chute; process until dough forms a ball. Process an additional 45 seconds. Turn dough out onto a lightly floured surface; knead lightly 4 to 5 times. Cover and let rest 30 minutes.
Roll dough into a 14-inch circle on a lightly floured surface. Place dough on a baking sheet sprinkled with cornmeal. Crimp edges of dough with fingers to form a rim. Sprinkle feta cheese evenly over dough. Combine onions, leek, oregano, 1 tablespoon oil, and 1/4 teaspoon salt; spread onion mixture evenly over pizza crust. Sprinkle with Parmesan cheese; bake at 425° for 25 minutes or until crust is lightly browned.