Uni? (San Fransisco near FiDi)
Santa Barbara Uni or Hokkaido?
If you like Santa Barbara (I do) I would say at least half of the good sushi bars will have it. Often on the whiteboard.
Fidi is short on good sushi though....
You might try calling Sebo - not that far from FiDi and they have a HUGE pile of uni in a picture on their website.
Sorry I can't be more specific - my sushi spots are down the peninsula these days, plumbing the depths of San Mateo Japanese keeps my tongue busy.