“My career has built step by step,” says Elina GarancA?a. “It’s a very quiet story.” The buzz got a lot louder in 2010 after GarancA?a’s “nuanced, sexy, and cagey” turn in the title role of the Metropolitan Opera’s Carmen (The New York Times). This is a singer who will astound you, whether singing the role of a Spanish temptress or in recital here at Carnegie Hall.