Just a little bit of acid phosphate, a much-loved old school soda fountain ingredient, adds a distinct tartness to this homemade chocolate soda.
Note: You can order acid phosphate online here.
- Yield:1 soda, makes enough chocolate syrup for 8 sodas
- Active time: 15 minutes
- Total time:15 minutes
- For the Homemade Chocolate Syrup:
- 2/3 cup (1.75 ounces) cocoa powder
- 1 cup (7 ounces) sugar
- 1 cup water
- Pinch of salt
- For the Soda:
- 8 ounces seltzer
- 3/4 teaspoon acid phosphate (see note)
- 3 tablespoons homemade chocolate syrup
For the Chocolate Syrup: Combine cocoa, sugar, water, and salt in a small saucepan and bring to a boil over medium-high heat, stirring frequently. Keep your eye on the syrup as it approaches boiling because it's prone to boil over. Immediately reduce the heat to low and keep the syrup at a steady simmer until it reduces enough to coat the back of a spatula, about 10 minutes. Remove from heat, cool to room temperature, and store in the refrigerator.
For the Soda: Place seltzer, acid phosphate, and chocolate syrup in a highball or other tall glass. Stir to combine. Top each glass with ice to fill and serve immediately.