The long hallway that leads back to the Pearl District's Fratelli is probably there out of necessity but seems ingenious in the way that it kindles curiosity. When you finally step into the dining room, the exposed kitchen, polished concrete floor criss-crossed with Oriental rugs, and towering beams and skylights all seem enterprising and a bit clandestine. Since 1998 Fratelli has specialized in romantic, candlelit Italian cuisine fine-tuned for Portland palates, favoring local flavors such as wild mushrooms, raspberry coulis and Cattail Creek Farm lamb. (LC)