Place the sugar cube or 1/2 teaspoon loose sugar in an Old-Fashioned glass.
Wet it down with 2 or 3 dashes of Angostura bitters and a short splash of water or club soda.
Crush the sugar with a wooden muddler or whatever. Rotate the glass so that the sugar grains and bitters give it a lining. Add a large ice cube. Pour in the rye or bourbon.
(Recipe courtesy Esquire.com)