Place pizza stone in oven and heat to 425 F. Brush breads with olive oil and place on stone in oven until crisp (about 5-7 minutes). Carefully remove breads from oven and place on cutting board; cool 1-2 minutes. In small bowl, combine sour cream, cream cheese, red onion, lemon zest, capers and lemon juice. Spread mixture evenly over both breads. Top each with salmon slices, overlapping to cover entire bread. Sprinkle dill and freshly ground black pepper over salmon. Slice each bread into 6 pieces.