New Shanghai on Convoy St., between Balboa and Clairemont Mesa on the west side of the street, is amazing. Not only are they inexpensive, generous, and delicious, they are also open until midnight. You don't see too many white folks in there, and some of the items on the menu may disturb you with their authenticity (Pork Hand Tendon, anyone?) but they are worth a try.
They have both a standard menu, and a specials menu. The specials menu varies based on time of day, so if you hit the 6-9pm time slot, you'll get one specials menu, with a different one in effect from 9pm-midnight.
If you are there for the 6-9pm, there is a dish called "Braised Oilless Pork Shoulder". This is incredibly good, and an incredible bargain - as you get an entire pork shoulder for $7.25. Do not order this solo, unless you plan to eat about 3 pounds of meat.