Matiki Island BBQ is a great choice about a mile away from Knott's, on Lincoln just west of Beach.
Musubi Square off La Palma & Magnolia is another one you can try and is good for takeout. My wife picked it up for dinner the other night and the eel musubi taco was awesome.
And a little further out, give Maxwell Chicken Rice off La Palma & Valley View a try for some Hainan chicken rice.