In a small bowl, stir together 1/2 cup sour cream and 1 tablespoon prepared horseradish until smooth; set aside.
Use a vegetable peeler to shave the cucumber into long ribbons, rotating the cucumber until you reach the seeds and discarding the seedy core if desired.
Arrange cucumber ribbons and 8 oz sliced smoked salmon on plates by curling or folding them into small nests.
Dollop small spoonfuls of the horseradish-sour cream mixture around the salmon and cucumber.
Finish with lemon zest, a sprinkle of salt, and plenty of freshly ground black pepper; garnish with edible flowers or microgreens if using.
Equipment
Small Bowl
Vegetable peeler
Zester or microplane
Knife
Serving plates
Notes
Use a thin-skinned English hothouse cucumber for best ribbons.
Adjust horseradish amount to taste for more or less heat.