Chill a 12 fl oz glass or bottle and the carbonated water until very cold (this preserves carbonation). Measure 12 fl oz of carbonated water and keep it cold.

Add the high-fructose corn syrup (or prepared sugar syrup) and caramel color to the cold carbonated water. Stir gently with a long spoon — do not vigorously agitate — just enough to incorporate syrup without losing much carbonation.

Flavor Blend (concentrate)

In a small bowl or measuring cup, combine the cola flavoring syrup, cherry syrup, vanilla extract, almond extract (if using), black licorice or anise extract, prune/raisin concentrate and the spice blend (a tiny pinch of ground cinnamon, nutmeg and clove).

Whisk the flavor blend thoroughly until homogenous. Taste a very small drop; the blend should be intense and concentrated because it will be diluted into the 12 fl oz of carbonated water. Adjust by adding a touch more cherry for fruitiness or more cola extract for traditional cola notes. Use extreme restraint with the anise/licorice extract — a tiny amount goes a long way.

Add the measured flavor blend to the soda base in the cold carbonated water and stir gently no more than 6–8 slow strokes to mix the concentrate evenly.

Acid & Balance

Stir in the phosphoric acid solution (or a small amount of 10% citric acid solution) and the fresh lime juice. These acids provide the tart, tangy backbone similar to Dr Pepper and help brightenthe flavor. Stir gently to combine.

Taste the soda and adjust: if it tastes flat, add another 1/8 tsp of citrus or 1/8 tsp more syrup for sweetness; if too sweet, add a few drops more acid. Make adjustments in very small increments.

Garnish & Serve

Fill a serving glass with ice cubes (optional). Pour the prepared soda slowly over the ice to keep fizz. Garnish with a maraschino or fresh cherry and a lime wedge on the rim.

Serve immediately chilled. This yields one 12 fl oz serving. Store any unused flavor blend separate from carbonated water; mix fresh for best carbonation and flavor.