1. Combine 1/2 cup warm water and yeast in the bowl of a stand mixer with dough hook attached; let stand 5 minutes or until bubbly. Add oil and salt to yeast mixture. Weigh or lightly spoon flour into dry measuring cups; level with a knife. Sprinkle flour over yeast mixture; mix 2 minutes or until a soft dough forms. Place dough in a large bowl coated with cooking spray; cover surface of dough with plastic wrap lightly coated with cooking spray. Refrigerate 24 hours.
2. Position an oven rack in the lowest setting. Place a pizza stone on lowest rack. Preheat oven to 550°. Preheat pizza stone 30 minutes before baking the dough.
3. Remove dough from refrigerator. Let stand, covered, 1 hour or until dough comes to room temperature. Punch dough down. Roll dough out to a very thin 14-inch circle on a lightly floured baking sheet, without raised edges, sprinkled with cornmeal. Crimp edges to form a 1/2-inch border. Pierce dough several times with a fork.
4. Slide dough onto preheated pizza stone, using a spatula as a guide. Bake at 550° for 4 minutes. Remove from oven; spread cheese evenly over dough. Arrange capers and onion over cheese. Bake an additional 5 minutes or until crust is golden brown. Top evenly with salmon; sprinkle with dill. Cut pizza into 8 wedges.