We really like the chicken nachos at Tortilla Jo's in DTD (dine-in, not the outside counter service). Two people can split it and call that dinner. The rest of the menu seems pricey so we haven't ventured beyond the nachos to be honest.
A little further from DTD there is a counter service place called Los Sanchez, which is on Garden Grove Blvd south of DLR. The easy way to get there is go south on
Disneyland Drive (the street between GCH and PPH) until it ends at GG Blvd. Turn right then an immediate left into the parking lot. They have indoor seating and the place is always busy, which should tell you what you need to know.
Even further away in the city of Orange is the Chili Pepper, which is on Main St just south of Chapman. Great prices, fast service, and a pretty good Rosarita Margarita.