Peel the radishes with a vegetable peeler, so that some red is removed but some strips remain (as pictured). Use the tip of a knife to cut out the centers of the radishes. Add an olive half to the cut-out center of each radish. If using cream cheese, first add a pea-sized amount of cream cheese, then the olive slice.
For the Guacamole
Puree the avocado with lime juice and paprika or cayenne in a blender until smooth. Add a touch of water or olive oil if necessary to thin out the guacamole slightly, if too thick to blend. Pour into a bowl, garnish with chopped cilantro, and serve alongside the stuffed radishes.