OK, so this isn't strictly a Manhattan question, but I did have it at Ise on Pine St last week. As part of one of their variety-of-dishes-in-a-box dinners, one compartment had two approximately 1" cubes of pork belly in a dark and smoky sauce. Not listed as a component on the menu, and quite a surprise to me. What was this stuff? It was good in only the way pork fat can be, but just seemed uncharacteristic for a Japanese dinner.
Ise, incidentally, is a very nice restaurant. I've eaten there twice in the last few months -- they re-opened on Pine St last Sep, I think, after closing their prior location after 9/11. Once I sat at the bar and ate just sushi, which was all very satisfying and well-presented (and not super-sized, as seems popular in lesser places.) This time I sat at a table and had a full dinner, which also was almost uniformly excellent (I've eaten better tempura in Japantown in SF, but it wasn't "bad" at Ise, just not excellent.) Very friendly service, nice clean space.