Three friends and I will be spending a Friday together in San Francisco, near the Embarcadero, and we're looking for a restaurant with fabulous food and a mellow vibe where we can catch up and talk. Our price range is moderate: between, say, $15 and $30 for entrees. We would like the restaurant to be within a 15-minute range by foot, taxi, or public transportation. We're open to different kinds of food but are especially drawn to fresh and local (of course). Does anyone have suggestions?