01 - In a small saucepan, combine the honey, lemon juice, water, raspberries or strawberries, and sugar if using. Gently mash the berries with a muddler or fork. Heat over low heat for 2 to 3 minutes, stirring continuously, until the honey fully dissolves and the mixture takes on a vibrant pink color.
02 - Pour the mixture through a fine-mesh sieve into a bowl or jug, pressing firmly on the fruit to extract maximum color and flavor. Discard the solids and set the strained syrup aside to cool slightly.
03 - Fill four serving glasses generously with ice cubes. Divide the pink honey-lemon syrup equally among the glasses.
04 - Pour chilled sparkling water or club soda over the syrup in each glass, filling to the top. Stir gently to combine without losing the carbonation.
05 - Finish each glass with a lemon slice and a sprig of fresh mint. Serve immediately while cold and fizzy.