A fellow hound recommended the al pastor from the market at the corner of Hammond and Summit in Pasadena (it has no name) and I tried it today and it was indeed excellent.
This place is a corner market with a guy who cooks in the back. They make all sorts of tacos and burritos and the menu is on a marker board outside.
I had two carnitas (w/ green sauce) and two al pastor (w/ red sauce) tacos.
And even though the original post-er was praising their pastor, I thought it was their carnitas that was even better: just enough fat to cut through the dryness making a perfect blend of chewy and moist.
(I would have linked this to the original post but i couldn't find it)