The first, and most important part, is to make a rhubarb-rosemary simple syrup:
Combine the rhubarb-rosemary syrup with a clear alcohol; I used vodka, but gin or white rum would work just as well. The ratio is 1 part syrup to 1 part alcohol, but should be adjusted to taste. For a mocktail version, dilute the syrup with seltzer water. Garnish with a fresh spring of rosemary and enjoy!
Jane (05/07/2014 9:04pm): Lovely looking cocktail. The colors make me think of Spring!