Slice the cucumbers thinly using a sharp knife or mandoline. Place in a colander set over a bowl and toss with 1/2 teaspoon kosher salt. Let drain for 10 minutes to remove excess moisture.

While cucumbers drain, in a medium bowl whisk together mayonnaise, sour cream, chopped dill, lemon zest, lemon juice, minced shallot, remaining 1/2 teaspoon salt, and black pepper until smooth and well combined.

Gently fold the crab meat into the dressing mixture, being careful not to break up the lumps too much.

Pat the drained cucumber slices dry with paper towels or a clean kitchen towel to remove as much moisture as possible.

Add the dried cucumber slices to the crab mixture and fold gently until evenly distributed.

Taste and adjust seasoning with additional salt, pepper, or lemon juice if needed.

Serve immediately garnished with extra dill sprigs and lemon wedges on the side.