Wash lemons thoroughly under running water
Roll each lemon on countertop to loosen pulp
Cut lemons in half and juice using manual or electric juicer
Strain juice through fine mesh sieve to remove seeds and pulp
Measure 1 cup of juice; adjust with additional lemons if needed
Combine 1 cup sugar and 2 cups cold water in saucepan
Heat over medium-low until sugar fully dissolves (5-7 minutes)
Remove from heat and let syrup cool completely
Stir in strained lemon juice once syrup reaches room temperature
Top off with remaining 2 cups cold water for desired strength
Refrigerate mixture for at least 1 hour to develop flavors
Fill glasses with crushed or cubed ice depending on preference
Pour chilled lemonade into glasses
Garnish with mint leaves and thin lemon slices (optional)