Peel the avocado and cut into quarters. Slice thinly, drizzle with lemon juice, season with salt and pepper. Arrange on bread 'overlapping' and spread with a knife like butter.
Place egg slices and radish slices on top of the avocado, season with salt and pepper. Drizzle with olive oil mixed with Dijon mustard and sprinkle with chives or torn basil.