In a heavy-bottomed small saucepan, combine ⅓ cup granulated sugar with ½ cup water Bring the mixture to a boil, reduce the heat to low, and simmer until the sugar is dissolved. Once the sugar is dissolved, remove the pan from the heat.
Place mint leaves into a heat-safe mixing cup or cocktail shaker and add the simple syrup. Using a wooden spoon or muddler, gently mash the mint leaves 4-5 times, allowing the mint to release their juices. Let the mint leaves steep in the warm simple syrup for 10 minutes.
While the mint is steeping, juice 6 large lemons over a fine-mesh strainer to catch any seeds or pulp until you have ¾ cup of lemon juice.
Using a fine-mesh strainer, strain the mint leaves from the simple syrup.
In a large pitcher, combine the remaining 5 cups water, lemon juice, mint flavored simple syrup, and 1 cup ice.
Serve with additional ice, sliced lemon, and mint leaves as desired.
Notes
Tip for Juicing Lemons: Before cutting open the lemons, microwave the lemons for 20 seconds and then roll them on the counter. This will help to get the juices flowing. Mint: This recipe uses fresh spearmint, which is what is typically sold at most grocery stores and is simply labeled mint. Sugar: This recipe is made with less sugar than most lemonade recipes. However, if you like sweeter lemonade, feel free to increase the amount of sugar added. I have personally not tried this recipe using any sugar substitutes. Storing: Store Mint Lemonade in the refrigerator for 5-7 days.