To make the smoked pork belly bitters: In a skillet, cook smoked pork belly until crisp. Add the pork belly and the fat to a jar with 8 ounces of Angostura Bitters. Let cool. Seal tightly and freeze for at least 24 hours. Spoon off the solidified fat and strain through a cheese cloth. Bottle.
To make the cocktail: Still all the ingredients together and serve on the rocks in an Old Fashioned glass. Enjoy immediately.