Prep the cucumber: Trim the ends.
If using an English cucumber, you can leave the peel on for texture and color. Slice into 1/2-inch rounds for sturdy bases.
Salt lightly (optional): For extra-crisp bites, sprinkle a pinch of salt over the rounds and let them sit on a paper towel for 10 minutes. Pat dry to remove moisture.
Soften the cream cheese: Let it sit at room temperature for 15–20 minutes so it blends smoothly without lumps.
Make the filling: In a bowl, mix cream cheese, sour cream (if using), lemon juice, lemon zest, chives, dill, garlic, onion powder, salt, and pepper.
Stir until smooth and fluffy. Adjust seasoning to taste.
Pipe or spoon the filling: Transfer the mixture to a piping bag or a zip-top bag with a corner snipped off. Pipe a small swirl onto each cucumber slice.
If you don’t want to pipe, spoon a dollop and smooth the top.
Add garnish: Finish with a pinch of red pepper flakes, smoked paprika, everything bagel seasoning, or sesame seeds. A few extra chives on top look great too.
Chill briefly: Refrigerate for 10–15 minutes to help the topping set and the flavors meld. Serve cold.