Prep the Cucumber: Peel (if needed) and thinly slice 1 large cucumber (1/16 inch thick). Sprinkle with salt, let sit for 10–15 minutes in a colander, then pat dry with paper towels.
Mix the Spread: In a bowl, combine 4 oz softened cream cheese, 2 tbsp softened butter, 1 tbsp chopped dill, 1 tbsp chopped chives, 1 tsp lemon juice, and a pinch of salt and pepper. Stir until smooth.
Spread on Bread: Spread a thin layer of the cream cheese mixture on one side of 8 slices of soft white bread.
Add Cucumbers: Place a single layer of cucumber slices on 4 of the bread slices. Sprinkle lightly with salt and pepper.
Assemble Sandwiches: Top the cucumber-covered slices with the remaining 4 bread slices, cream cheese side down, to form sandwiches.
Trim and Cut: Use a serrated knife to cut off the crusts, then slice each sandwich into 2–3 small pieces (triangles, rectangles, or squares).
Serve: Arrange on a platter and serve immediately, or cover with a damp paper towel and plastic wrap to keep fresh for up to an hour.