Pour the teaspoon of sugar into your rocks glass and add the Angostura bitters. The bitters help dissolve the sugar and create the flavor base everything else builds on.

Cut a thin slice of orange, about 1/4 inch thick. Hold it over the glass and twist it slightly to release the oils; you should see a fine mist of citrus oil spray across the glass surface.

Add the orange slice to the glass with the sugar and bitters. Using a muddler or the back of a spoon, press down gently and twist for about 10 to 15 seconds, just enough to bruise the orange and help the sugar dissolve. Aggressive muddling tears the fruit and makes the drink bitter; you want gentle coaxing, not pulverization.

Pour 2 ounces of brandy into the glass. Stir gently for about 10 seconds, letting the brandy blend with the sugar, bitters, and orange oils.

Add ice to the glass, preferring one large cube or several large cubes over crushed ice. Large ice melts slowly, keeping your drink cold without diluting it into weakness as it sits.

Pour 2 to 3 ounces of soda water or lemon-lime soda into the glass, depending on how strong you like your cocktail.

Using your bar spoon, stir the entire drink for about 5 seconds, blending the brandy, soda, and orange flavors evenly throughout.

Add a maraschino cherry to the glass if desired. Serve immediately and enjoy.