1. Preheat the oven to 160°C (325°F).

2. In a bowl, combine graham cracker crumbs and melted butter until evenly moistened.

3. Press the mixture firmly into the bottom of a 20 cm (8-inch) springform pan.

4. Bake the crust for 10 minutes, then remove and let cool completely.

5. In a large mixing bowl, beat cream cheese, sour cream, lemon zest, and dill until smooth and creamy.

6. Fold in the chopped smoked salmon, smoked paprika, and black pepper.

7. Pour the mixture over the cooled crust and smooth the top with a spatula.

8. Chill in the refrigerator for at least 3 hours, or until fully set.

9. Just before serving, arrange cucumber ribbons and sliced radishes in a spiral or overlapping pattern on top.

10. Cut into 8 slices using a sharp knife dipped in hot water.

11. Serve with lemon wedges on the side.