Estadio, a new Spanish restaurant from the owners of Proof, opens today at 1520 14th Street NW. The restaurant will serve a range of Spanish tapas and “slushitos,” which are essentially alcoholic slurpees. In preparation, check out Jane Black’s mouth-watering article about Chef Haidar Karoum and owner Mark Kuller’s journey through Spain to figure out what to bring to the table. Much like Proof, there will interesting bathroom decorations; Estadio will carry on the…