Top each slice of bread with a slice of cucumber, 1 teaspoon of the sour cream mixture, a sprig of dill and a slice of salmon.
Ingredient Note: Greek-style yogurt is made by removing the whey from cultured milk. Removing the whey gives it an extra thick and creamy texture - making it the perfect ingredient for a lower-fat dessert topping. You can strain regular yogurt to make it thick like Greek-style yogurt. Line a sieve with cheesecloth and set it over a bowl. (Alternatively, use a coffee filter lined with filter paper.) Spoon in 1 cup nonfat plain yogurt and let it drain in the refrigerator until reduced to 3/4 cup, about 2 hours.