Slice the cucumber in to thin discs, about 1/4 cm thick, Place cucumber discs in a mixing bowl along with the salt and stir well to combine. Set aside for 15 minutes to allow the cucumber to release any excess liquid.
Meanwhile, finely slice the scallions and roughly chop the dill. Place in a small mixing bowl.
Add the sour cream, mayonnaise, lemon zest, lemon juice, and black pepper to the scallions and dill. Stir well to combine.
Drain any excess water from the sliced cucumber and bolt with a paper towel to absorb any remaining moisture.
Spoon the creamy dressing over the cucumber discs and stir well to coat, refrigerate until ready to serve