In a small saucepan, combine the white sugar and 1 cup (240 ml) water. Heat gently over medium heat, stirring just until the sugar fully dissolves and the liquid turns clear. Do not allow the mixture to boil — aggressive heat dulls sweetness and flattens citrus perception later. Remove from heat and let the syrup cool completely.

Juice 5–6 medium lemons to obtain about 240–300 ml fresh lemon juice. Strain out seeds but keep the juice natural and slightly pulpy — a small amount of texture improves structure and freshness. Taste the juice on its own; it should be bright and clean, not bitter.

In a large pitcher, combine the lemon juice with about two-thirds of the cooled simple syrup. Add 4 cups (960 ml) ice-cold water and the fine sea salt. Stir thoroughly until fully integrated. The drink should taste sharp and refreshing with controlled sweetness, never sugary.

Taste and adjust deliberately. Add more syrup only if acidity feels aggressive. Add small splashes of cold water if the lemonade feels too concentrated. Proper balance should feel crisp and drinkable rather than intense or heavy.

Cover and refrigerate for 1–2 hours. This resting period allows sweetness and acidity to fully integrate, creating a smoother and more cohesive flavor profile. Skipping this step often results in a drink that tastes thin or disconnected.

Fill glasses generously with ice, pour over the chilled lemonade, and garnish with lemon slices. Serve very cold for maximum brightness and refreshment.