In a small saucepan combine 0.5 cups cold filtered water, 0.75 cups high fructose corn syrup (or simple syrup made by dissolving equal parts sugar and water), 2 tablespoons brown sugar, 1 teaspoon molasses, and 1 teaspoon dark caramel syrup. Warm gently over low heat just until sugars are fully dissolved — do not boil. Stir constantly for about 2–3 minutes until homogeneous.

Add spices and flavorings

Remove the pan from heat and whisk in 1 teaspoon vanilla extract, 1 teaspoon ground allspice, 1 teaspoon ground cinnamon, 1/4 teaspoon freshly grated nutmeg, and 1/2 teaspoon citrus oil or the zest of half an orange. Add 1 teaspoon lemon juice (or a few drops of food-grade phosphoric acid substitute) to provide brightness and acidity. Taste carefully and adjust: if you want a darker, slightly burnt caramel note add up to an additional 1/4 teaspoon of caramel syrup; for more citrus brightness add a little more zest.

Cool and strain

Let the syrup cool to room temperature (about 10–15 minutes). Strain the syrup through a fine mesh sieve into a bowl or bottle to remove zest and any spice clumps. This yields your concentrated Mr. Pibb flavor syrup.

Assemble the soda

In a serving pitcher or glass, add 2 tablespoons (approx. 30 ml) of the concentrated flavor syrup per 8 ounces (1 cup) of carbonated water. For a 3-cup batch, add 6 tablespoons (3/8 cup) of syrup to 3 cups carbonated water. Gently stir once or twice with a spoon — avoid vigorous stirring to keep carbonation.

Chill and carbonate option

If you prefer extra fizz, chill the carbonated water well before mixing and pour syrup gently over ice in a glass, then add carbonated water. Alternatively, use a soda siphon or home carbonation device to freshly carbonate chilled water, then add the measured syrup.

Garnish / Serve

Fill a tall glass with about 1 cup ice cubes. Pour the prepared Mr. Pibb soda over the ice. Garnish with a lemon wedge or orange slice on the rim. Serve immediately with a straw.