Special equipment: a cocktail shaker and a martini glass
With a paring knife, slice one long slit down the length of the pepper and then four horizontal slits in the side of the pepper, making sure to leave the pepper whole and to avoid slicing it in half.
In a cocktail shaker filled with ice, combine the serrano, rum, orange liqueur, lime juice, tangerine juice, sugar and bitters. Shake and strain into a martini glass. Garnish with the lime slice.