Chill sparkling water and cold filtered water in the refrigerator for at least 30 minutes. Juice the oranges, lemons, and lime fresh. Finely zest one small orange and set aside a teaspoon.

If making simple syrup fresh: combine equal parts granulated sugar and water (for example 1/4 cup sugar + 1/4 cup water) in a small saucepan over medium heat. Stir until sugar dissolves and syrup is clear. Cool to room temperature before using.

Build the Drink

Muddle herbs

In a large pitcher, add the mint leaves and optional basil leaves. Gently bruise/muddle them with the back of a wooden spoon or a muddler just enough to release aromatic oils — about 8–10 presses. Do not pulverize; you want fragrance without bitterness.

Add the freshly squeezed orange juice (1 cup), cold filtered water (1 cup), fresh lemon juice (2 tbs), fresh lime juice (1 tbs), orange zest (1 tsp) and simple syrup (2 tbs) to the pitcher with the muddled herbs. Stir vigorously for 15–20 seconds to combine and to help infuse the citrus with the herbs.

Taste the mixture and adjust sweetness — add up to 1 tbs more simple syrup if you prefer sweeter, or up to 1 tbs more lemon/lime for brighter acidity. Remember that sparkling water will dilute slightly when added.

Finish with sparkle

Just before serving, gently pour chilled sparkling water (3 cups) into the pitcher. Stir once slowly to combine and preserve carbonation. Do not over-stir.

Serve

Fill two tall glasses with 1 cup of ice each (about 1 cup per serving). Divide the drink between the glasses, pouring slowly to maintain fizz.

Garnish each glass with an orange wheel and a mint sprig. If desired, lightly clap the mint between your palms first to release aroma before placing on the drink.

Serve immediately while sparkling. Leftover unsparkled mixture (base without sparkling water) can be stored refrigerated up to 48 hours; add chilled sparkling water just before serving.