Add beet juice, lemon juice, chopped rosemary and maple syrup a small saucepan. Bring to a boil, reduce the heat, and allow the mixture to cook at a controlled boil for 5 minutes. Remove from heat and allow mixture to cool for 10 minutes. Use a fine mesh strainer to strain out the rosemary. Pour liquid into a sealable container and refrigerate until chilled. To make one martini, add 3 ounces of the rosemary beet juice infusion and 1.5 ounces of vodka to a shaker with ice. Shake until cocktail is chilled and foamy. Pour and enjoy!