Combine all ingredients in a cocktail shaker filled with clean ice (and a few mint leaves if you have them). Shake well for 10 seconds or longer. Strain through a fine mesh strainer. Garnish with crushed pink peppercorns or a mint leaf.
If using powdered egg whites, whisk a pinch into the lime juice to dissolve before adding the juice to cocktail shaker.
For the syrup:
Combine water and sugar in a pan and stir over medium high heat until sugar dissolves. Remove from heat, add mint and peppercorns, steep two hours. Strain to remove solids. Simple syrup keeps up to two weeks in the refrigerator.
Erik Eastman is the co-owner of Easy & Oskey, which sells a DIY Make Your Own Bitters kit. The video was produced by Jennifer Simonson for MPR News.