Prepare the Lemons: Roll the lemons on the counter to soften them. Cut them in half and juice them to get about 1 cup of fresh lemon juice.

Make the Sumac Syrup: In a small saucepan, combine 2 cups of water, sumac, and sugar. Heat over medium heat, stirring occasionally, until the sugar is completely dissolved. Let it simmer for a few minutes, then remove from heat.

Strain the Syrup: Strain the sumac syrup through a fine mesh sieve into a large pitcher to remove the sumac solids. Allow it to cool to room temperature.

Mix the Lemonade: Once the sumac syrup has cooled, add the fresh lemon juice and the remaining 2 cups of cold water to the pitcher. Stir to combine.

Chill: Refrigerate the lemonade for at least 30 minutes to allow the flavors to meld together.

Serve: Fill glasses with ice cubes. Pour the chilled sumac lemonade over the ice.

Garnish: Garnish each glass with fresh mint leaves.