Prepare the cucumber cups Wash the cucumbers and pat them dry. You can peel strips of the skin off to create a variegated look, or leave the skin intact for better structure. Slice the cucumbers into rounds about one inch thick. Use a small melon baller or a half-teaspoon measuring spoon to scoop out the center of each round, creating a small bowl. Do not scoop more than halfway through the slice. Place the slices upside down on a paper towel to drain while you make the filling.

Mix the salmon base Place the chopped smoked salmon in a food processor. Pulse five or six times until the fish is broken down into very small bits but is not yet a smooth paste. Adding the fish first ensures you don’t over-process the dairy later.

Combine with aromatics Add the softened cream cheese, Greek yogurt, lemon juice, lemon zest, and black pepper to the food processor. Process the mixture for about 30 seconds until it is completely smooth and light. If the mixture seems too stiff to pipe, add one more tablespoon of yogurt and pulse again.

Finish by hand Transfer the mousse to a small bowl and fold in the chopped fresh dill using a spatula. This keeps the dill from coloring the mousse green and preserves the visible flecks of herbs. Taste the mixture before adding any salt; the salmon is usually salty enough to season the entire batch.

Fill the cups Transfer the mousse to a piping bag fitted with a large star tip. If you do not have a piping bag, you can snip the corner off a heavy-duty plastic freezer bag. Pipe the mousse into the center of each cucumber cup, mounding it slightly above the rim.

Garnish and serve Top each cup with a small sprig of dill, a single caper, or a tiny slice of radish for color. These are best served within two hours of assembly. If you need to make them further in advance, store the mousse and the prepped cucumber slices separately in the refrigerator and assemble them just before your guests arrive.