Not sure if this is your thing, but the thing i miss most about southern California is the Asian food. Specifically in that area, Vietnamese food in Westminster and Korean food in Garden Grove.
I used to like a place called Lite Town House in Garden Grove for Korean BBQ. Not sure if it's still there or not, I heard it may have moved to Irvine. But there were lots of other good places there.
Vietnamese restaurants tend to be more hole in the wall places, but you can't beat the pho in Westminster.
Edit: there's a fast food chain called Lee's Sandwiches which serves Vietnamese banh mi sandwiches, there's probably a bunch around there.