Pink Grapefruit-Tarragon Sorbet

"Clean, fresh and icy-cold, this bracing tarragon-infused grapefruit sorbet is a perfect way to lift flagging spirits on a sultry day. Garnish with grapefruit zest and tarragon sprigs, if you like. Cranberry juice concentrate brightens the color, but can be omitted. Vodka helps smooth the texture, but it, too, can be left out if you prefer; just let the frozen mixture soften a bit before serving. This recipe also works well with 10 to 12 spearmint sprigs and 2 teaspoons chopped spearmint instead of the tarragon. Recipe by Nancy Baggett for EatingWell...."