This delightful version substitutes black current liqueur for the vermouth.
Ingredients:
Ice (enough to fill shaker about 3/4 full)
6 to 16 drops of creme de cassis
2 ounces gin or vodka
Black olive (for garnish)
Fill a shaker with ice. Add the creme de cassis and the gin or vodka. Stir or swirl lightly, and then strain into a martini glass. (Note: Can also be served in a rocks glass filled with ice, if desired.) Garnish with the black olive.