Step 1Heat the oven to 325 degrees. Place the prepared crust directly on the oven rack and heat until the crust is warmed through, about 5 minutes. Transfer the warmed crust to a cutting board.
Step 2Spread the sour cream over the crust, leaving a one-half-inch border. Sprinkle about half of the red onion over the sour cream and sprinkle half of the dill over the onion.
Step 3Lay the salmon slices over the pizza to cover the sour cream, onion and dill. Sprinkle the remaining onion and dill over the salmon, then scatter the capers over them. Cut the pizza into wedges and serve at once.