Fullerton to Los Angeles
In down town Fullerton, Roscoe's Deli is not bad for big sandwiches and beer and El Fortin on Commonwealth has excellent food (my friend said the mole was like her grandma' s and I was the only person in the place who was not a native speaker of Spanish). People say that Lee's on Harbor is the McDonald's of Bahn Mi, but it will do in a pinch.
In short, your best bets in Fullerton (fairly close off the 91) are Ruta's (fresh salads, sandwiches & great coffee), The Olde Ship (English) and The Cellar (for pricey French-ish fair); all are right off Harbor Blvd.
305 North Harbor Blvd, Fullerton/Anaheim, CA 92832
211 N Pomona Ave, Fullerton, CA 92832
The Olde Ship
709 N Harbor Blvd, Fullerton, CA 92832
Taps in Brea on Imperial Hwy is quite nice. They have great seafood dishes (drunken mahi mahi, ahi tuna, chilean sea bass, oysters) and chops. The bar is great, and the staff is really knowledgeable and attentive.
Taps Fish House & Brewery
101 E. Imperial Hwy., Brea, CA 92821