Well, why not? This is one language in which at least 80 percent of Miami-Dade County residents can claim to have some proficiency. Besides making millions for the likes of Ricky Martin and Gloria Estefan, bilingual performance, when done well, provides an entertaining aural experience and an intriguing oral history, as Michael John Garces proved in Agua Ardiente, the show he wrote and directed.Of Cuban, Colombian, and American origins, Garces skillfully scripted his heritage through a lusty and heartbreaking array of personae. The one-man performance was both soliloquy and son, monologue and dialogue; it was an ode and a diatribe, a rant and a meditation. Garces's mastery of various poetic styles (language poetry, beat poetry, and spoken word) and his strong theatrical foundation made Agua Ardiente not a grab bag of form and language but an organic and energetic piece of bilingual drama.