If you want the real ceviche, go to this Peruvian restaurant in El Sobrante. The Mexicans may have made it popular here, but Peru takes credit for inventing the dish. According to food historians, the Incas would marinate fish in sour juices to cook it. The Spanish contributed limes and onions, and 19th-century Japanese immigrants lightened the acid to let the flavor of the fish come through. Which, arguably, makes El Chalan's version definitive, and delicious. On your plate you'll find a thick slab of boiled sweet potato, spoonfuls of crunchy, nutty, roasted field corn, and a mountain of whitefish, tart and piscine, covered in a heap of finely shaved red onions. Squirt on a bit of El Chalan's five-alarm ají (dried chile) sauce, and let your mouth have it -- sweet vs. sour, crunchy vs. tender, comforting vs. incendiary. Cool off afterward with a glass of chicha, a sweet drink made with purple corn, pineapple juice, and spices, and don't walk out of the restaurant without taking a few buttery alfajores, cornstarch cookies, with you.