Combine 1 cup water and 1 cup granulated sugar in a small saucepan. Warm over medium heat, stirring until sugar fully dissolves. Bring to a gentle simmer for 1 minute, then remove from heat.

Stir in 1 tablespoon light brown sugar and 1 teaspoon invert syrup or corn syrup while still warm until incorporated. This increases mouthfeel and helps carbonation retention. Let syrup cool to room temperature.

Flavoring Concentrate

Place the following in a small heatproof bowl or jar: 1 tablespoon fresh lime juice, 2 teaspoons fresh orange juice, 1 teaspoon vanilla extract, and 1 teaspoon grated citrus zest (combined lime + orange).

Add 1 teaspoon cola extract (commercial cola flavoring) or an equivalent homemade concentrate. If using commercial extract, start with 1/2 teaspoon and adjust to taste. Stir to combine.

In a small dry skillet, toast 1/4 teaspoon crushed coriander seed for 15–30 seconds until aromatic; remove and cool. Add toasted coriander, 1/2 teaspoon broken cinnamon stick (or 1/2 tsp powdered cinnamon if necessary), 1/4 teaspoon freshly grated nutmeg, and 1/2 teaspoon dried orange peel (or a few drops orange oil) to the flavor mixture. If you used whole spices, bruise them slightly or briefly steep them in 2 tablespoons of the warm simple syrup for 5–10 minutes to extract flavor, then strain out solids back into the syrup.

Taste the concentrated mixture and adjust: more vanilla for roundness, more lime for bite, or a touch more cola extract for characteristic cola notes. Aim for a bright, slightly bitter-sweet concentrated syrup — it should be stronger than a finished soda because it will be diluted.

Finish & Carbonation

Combine the cooled simple syrup and the flavoring concentrate: mix the cooled syrup (from Syrup Base) with the prepared flavor concentrate. Stir thoroughly. This yields a cola concentrate. For clarity, strain the combined syrup through a fine mesh sieve or coffee filter to remove zest and spice solids.

Mix final drink: For each serving (about 12 fl oz / 355 ml), use approximately 2 to 3 tablespoons cola concentrate and 10–11 ounces (about 1 1/3 cups) very cold club soda or carbonated water. In this recipe batch, pour 4 cups very cold club soda over ice into a pitcher or individual glasses and slowly stir in 3/4 to 1 cup of the prepared cola concentrate (adjust sweetness/strength to taste). If you prefer bottled-style sweetness, start with 3/4 cup concentrate for 4 cups soda and adjust next time.

Serve: Fill glasses with ice, pour the mixed soda, give a gentle stir to combine. Garnish with a lime wedge. For an authentic 'Coca Cola Mexicana' feel, use glass bottles or serve chilled with a lime on the rim.

Storage: Keep leftover cola concentrate refrigerated in a sealed jar for up to 2 weeks. Mix with cold carbonated water as needed (ratio 2–3 tbsp concentrate per 12 oz soda).