Add the sugar and bitters. Place the sugar cube in a rocks glass, then add the Angostura bitters. Add a small splash of club soda or a teaspoon of water if you like; this helps the sugar dissolve.

Muddle gently. Using a muddler or the back of a spoon, press the sugar cube softly until it mostly dissolves into a syrupy paste. Go easy — you want to break down the sugar, not pulverize it.

Add the bourbon. Pour in your 2 ounces of bourbon and give it a gentle stir to combine with the sweetened bitters base.

Add the big ice cube. Drop in one large ice cube — or a few standard cubes if that's what you have. The bigger the ice, the slower it melts, and the better your drink tastes to the last sip.

Stir to chill. Stir the cocktail for about 15–20 seconds, until it's nicely chilled and just starting to dilute.

Express the orange peel. Hold the peel over the glass with the pith facing away and give it a firm twist. You'll see tiny droplets of citrus oil spray across the surface — that's the magic. Rub the peel around the rim, then drop it in.

Garnish and serve. Add your cherry if using, give it one final gentle stir, and enjoy immediately.