S1, E4: You'll be needing those sweatpants with the elasticated waistband after overindulging on this culinary treat. The Spanish city of San Sebastián is a foodie hotspot, featuring some of the finest restaurants on the globe. But it's not all edible gas and quinoa. There's the traditional tapas bar that boasts the finest tortilla found anywhere and the restaurant that only features one menu item: steak.