Right now, my favorites are
Hwang Hae Do BBQ: for their lunch special mool naengmyun (buckwheat noodles in cold beef broth)
$2.99 from I think 11-3 and they only serve I think 150 bowls and that's it. They don't have that many toppings on it, but I've had the naengmyun a couple times and I feel it's very good, esp at this price. Unfortunately I do not believe anybody speaks English here, but just say "mool nengmyun" and they'll get you some. Service is slow though, they make everything to order. Also,they have a special where you can get mandu (potstickers) and moolnaengmyun for $5.99. I haven't tried their bbq or other stuff. $2.99 mool naengmyun! Get it before they come to their senses!
Hwang Hae Doh Restaurant
9567 Garden Grove Blvd
Garden Grove 92844
Hangari Noodle House
Their neng kongguksu (noodles in cold soymilk) is the best I've had so far in OC, and actually L.A. too, but I've failed to follow up on a couple of leads there so that doesn't count. No need to salt this soy milk. The soy milk is creamy and rich and has a rounded nuttiness that stands up on its own. The chill of the soup is particularly nice in this blazing weather. I cannot believe I haven't tried the soy milk noodles here before but well, now I know.
Hangari Noodle House (they speak English here)
9916 Garden Grove Blvd
Garden Grove, CA