1. Lightly toast the slices of bread and let cool.
2. Roughly chop the basil leaves. With a mortar and pestle, pound the butter, leaves and pepper together until well mixed. Alternatively mash butter, leaves and pepper together with the back of a sturdy spoon.
3. Smear each slice of toast with 1/2 tbsp of herbed butter. Arrange radish slices on top and sprinkle with sea salt. Enjoy!