Step 1: In a medium saucepan, combine 1 cup of granulated sugar with 1 cup of water. Heat over medium heat, stirring constantly, until the sugar is completely dissolved. Do not boil. Remove from heat and let it cool completely to room temperature. This is your simple syrup.
Step 2: Roll 8-10 fresh, ripe lemons firmly on a countertop for a few seconds. This helps to release more juice.
Step 3: Cut the lemons in half and juice them using a citrus reamer or juicer. You should aim for approximately 1.5 cups of fresh lemon juice. Strain the juice through a fine-mesh sieve to remove any pulp or seeds.
Step 4: In a large pitcher (at least 2-quart capacity), combine the cooled simple syrup and the strained lemon juice.
Step 5: Add 4-5 cups of cold filtered water. Start with 4 cups and taste. Add more water, a quarter cup at a time, until you reach your desired level of tartness and sweetness.
Step 6: Stir everything together thoroughly.
Step 7: Chill the lemonade in the refrigerator for at least 1-2 hours before serving. This allows the flavors to meld and ensures it’s perfectly cold. Serve over ice with lemon slices and fresh mint, if desired.