Make a simple syrup by bringing sugar and water to a boil over medium-high heat, stirring constantly to prevent scorching. When clear, remove from heat and let stand until just warm. Pour into clean 1-quart jar with tight-fitting lid. Add flavoring and vodka, cover, and shake well. This cordial may be served immediately, but it's better if allowed to age for 1 month.
Yield: approx 1 fifth