I have eaten at many Mexican restaurants in the Bay Area, and this is the best price/value place.
For dinner, I ordered a steak super burrito, which costed only about $6, was so big that I could not finish it (I am a male of average height and weight with a good appetite). So I took the leftover home and had it for lunch the following day.
In the past, I had had tacos, enchiladas, super burritos with tongue or with pork and they were all delicious. But my favorite is steak burrito. Salsa and chips are free so you can eat as much as you want. Order a Mexican soda or a beer with your burrito and the total is still less than $10. Where in the Bay Area, or even in the rest of the US, can you find a delicious, sit down dinner for this price?
This place is bare bone and cafeteria style, so don't expect a fancy restaurant. You order your meal at the counter and a staff member will bring it to your table. Tipping is not necessary, but I generally leave a dollar or two on the table because I enjoy my meal so much.
There is a patio area where you can dine at when the weather is nice. Weekend at lunch time is really crowded with families. But dinner time is never crowded both on weekdays or weekends.
This place is only a couple of blocks from the Fruitvale Bart Station. There are also lots of buses that run along International Blvd. (E. 14th Street), or along 35th Avenue, so getting there is super easy even if you don't drive.