Combine butter with the spices and lemon zest in a bowl, mixing well. Set aside.
Slice your cucumber into thin 1/8-inch rounds. Slice a few, very thin slices of lemon; take out any seeds and cut into very tiny wedges.
To assemble, spread a nice layer of dill butter on a slice of frozen bread (using frozen bread keeps the sandwiches from getting messy while assembling). Use a flower-shaped cookie cutter and cut out the sandwich.
Place a cucumber and a tiny lemon wedge on top of the sandwich.
Keep sandwiches in a sealed container in the refrigerator until ready to serve.
Right before serving, lightly sprinkle sea salt on the tops of the sandwiches.