Cut cucumbers in half lengthwise and thinly slice. In a bowl, mix cucumbers with 1 teaspoon salt; cover and chill at least 30 minutes or up to 4 hours.
Drain well and pat dry.
Separate egg yolks and whites.
Cut whites into slivers.
Add to cucumber.
In a blender or food processor, combine yolks, sour cream, vinegar, mustard, sugar, and pepper; whirl until smooth.
To serve, mix sour cream dressing and dill with cucumbers.
Add salt to taste. Line a wide bowl with lettuce leaves and spoon cucumber salad onto leaves.