Mint soak in water for a few minutes and rinse well under running water.
Pour water, bring to a boil and simmer for 15 minutes. Withdraw.
Add to the mint broth sugar, lime slice, citric acid and cook stirring over medium heat for 10 minutes.
Syrup cool, strain, add vodka and mix well, you can add a fresh sprig of mint to the bottle, which is removed after 5 days ( for a more pronounced taste ). For a brighter color, you can add food coloring.