Wash the dill, shake dry and pluck the tips off the stalk. Wash lemon hot, grate dry and cut in half. Cut off 2 slices from the lemon. Squeeze the rest of the lemon. Spread 1 teaspoon of butter on each slice of bread, place crabs on top and sprinkle with some lemon juice. Garnish slices with 1/2 slice of lemon and dill tips