Muddle grapefruit wedges, grapefruit juice, sugar, and spicy syrup in a highball glass. Slap mint between your hands and add o glass. Add rum, orange liqueur and ice. Top it with sparkling rosé. Garnish with mint sprig.
*To make chili pepper syrup, dissolve 16 oz. granulated sugar in 8 oz. hot water. Add one whole Serrano pepper, let chill in refrigerator overnight.