Slice cucumber into thin rounds (you will probably only need ½ the cucumber, depending on how thick you decide to make your slices).
Place smoked salmon slices on top of each other and slice thinly, then rotate the cutting board and slice again so that you have small squares. (If you have smoked salmon lardons, then cut into small cubes.)
In a medium bowl, whisk together crème fraîche, lemon juice, dijon mustard, pepper, and 1 teaspoon of the dill.
Gently fold in salmon.
Spoon salmon on top of cucumber rounds, then sprinkle with additional teaspoon of dill and serve.
Video
Notes
Make-Ahead: You can make this appetizer ahead of time, though I would not recommend making it much more than a few hours ahead of serving. You can prep all the ingredients, including slicing the cucumber, and stir together the salmon mixture. From there, refrigerate separately. When it’s time to serve, spoon the salmon onto the cucumber rounds and garnish with chopped dill. Storing Leftovers: If you have leftovers of these canapés, you can store them in an airtight container in the refrigerator for about 24 hours. Unfortunately, they won’t freeze well.