In a rocks glass or julep tin, add the bourbon and peach liqueur. Fill the glass with crushed ice. Express an orange twist by removing the orange zest from the pith. Using a sharp knife cut along the outside of the orange removing as much of the skin as possible and taking as little of the white. Squeeze the orange peel on top of the drink to express the citrus oil. Discard the peel. Garnish with the mint sprig.