1. Heat oven to 400 degree F. Cut each slice of bread into 4 rectangular pieces. Arrange bread in an even layer on a large cookie sheet. Bake until tops are lightly toasted and golden, 5 minutes. Turn bread slices and bak 3 minutes more, until firm and toasted through. Transfer toast to a wire rack and let cool completely.
2. In a small bowl, combine sour cream, tarragon, lemon peel, salt, and pepper until well blended. Spread 1 piece of toast with about 1 teaspoon sour cream mixture. Roll up one end of a slice of salmon, leaving the other end flat. Place paprika in a shallow pie plate, then carefully dip both long edges of salmon roll in paprika. Place atop sour cream. Repeat with remaining sour cream mixture, toast, salmon, and paprika. Garnish each toast with a sprig of fresh tarragon, if desired. Makes 24 pieces.