Before you are ready to bake the pizzas, preheat the oven with a pizza stone inside for 30 minutes to 500 degrees F.
Cut the salmon into paper-thin slices. Reserve.
Roll or stretch the dough into 4 (8-inch) circles. Place the pizzas on a lightly floured wooden peel. Brush the center of each pizza to within 1 inch of the edge with olive oil and sprinkle it with some of the red onion. Slide the pizza onto the stone and bake 8 to 12 minutes or until crust is golden brown. Remember that the oven is very hot and be careful as you place the pizza into and out of the oven.
Mix the dill with the sour cream or creme fraiche and freshly ground pepper to taste. Transfer the pizzas to heated dinner plates and spread them with the sour cream mixture.
Divide the salmon, and arrange decoratively over the cream. Place a spoonful of golden caviar in the center of each pizza, then spoon a little of the black caviar into the center of the golden caviar.