There are a good number of Asian places worth a look on Post Street in the 3 or 4 blocks west of Powell. There is a burger place called Pearl's on the north side of Post that has gotten good reports. Canteen (817 Sutter) is VERY good, but lunch will run more than $10.
Also a few blocks towards Union Sq. at Grant is E&O Trading Co you can get a salad and some dishes around 13.00
I have not been here but my friend goes for lunch- Sanraku, Japanese and sushi
Sutter Cafe 330 Sutter at Stockton garage- good tamales- near my dentist and always rewarding after the trauma.