Mix together the cranberry juice, sugar, lime zest, and sodium citrate. Mix until all the sugar and sodium citrate have dissolved.
Whisk the liquid and sprinkle in the sphere magic. Allow the mixture to hydrate for 20 minutes.
Strain the liquid through a 250 micron superbag to remove the lime zest.
Mix water, sugar and calcium lactate in a small pot. Heat the mixture over medium high heat until it begins to simmer.
Cool the liquid completely before using.
Pour the calcium syrup, water, and citrus vodka into a martini glass.
Alternately place the calcium syrup, water, and citrus vodka into a cocktail shaker with a few Ice cubes. Stir for 15 seconds before straining into a martini glass.
Fill a spherificator with the cranberry liquid, let the spherificator dispense the spheres into the cocktail.
With the spherificator its best to keep moving the spherificator to help prevent the spheres from sticking together.
Stir gently before serving.