2 cups water
1 cup white sugar
2 cups thinly sliced rhubarb
1 1/2 fluid ounces good-quality vodka
1/2 fluid ounce triple sec liqueur
1 cup crushed ice
To make the rhubarb syrup, place sugar and water in a saucepan and bring to a boil over high heat, stirring occasionally. Lower heat to medium, and stir the rhubarb into the syrup. Simmer until rhubarb is softened and stringy, 5 to 7 minutes. Press out the juice with a spoon while straining syrup through cheesecloth or strainer into a glass jar or bottle. Discard rhubarb solids. Cool, and refrigerate syrup until needed.
To make a 'Barbtini, combine the vodka, 2 tablespoons rhubarb syrup, and triple sec in a shaker with ice. Shake until the outside of shaker is frosty. Strain into a martini glass.