The Store on the Corner - FiDi Korean
I had the jap chae for lunch, with tax it came to $5.35. Pretty good, big helping, excellent value by FiDi standards. I'd get it again. Nice day to sit outside at Yerba Buena Gardens.
They also have kim bap, bi bim bap, bulgogi, and a couple of other dishes.
121 New Montgomery, corner of Minna, counter in the back of a little liquor store.