Trim stem and root ends of radish.
Use a paring knife to scrape red skin
from radish, leaving just enough to give
a veiny appearance. With a small melon
baller, cut a hole in radish, about 1/2 inch
in diameter. Fit an olive half, cut-side
facing out, into hole. Place radish in
ice-cube tray. Repeat with remaining
radishes. Fill tray with water; freeze.
Mix vodka or gin with vermouth;
stir with ice. Divide eyeball ice cubes
among four glasses. Strain martini;
pour into glasses, and serve.