The new Oaxacan truck that parks at night at Bundy and Santa Monica (not the cemitas poblanas truck) makes a very good tlayuda. While the toppings aren't as wonderful as the lengua at the Rose/Lincoln truck, the tlayudas have a bit more zip and the bean stuff is more flavorful. Good.
I've read a lot of postings lately that say all taco trucks in L.A. serve up good stuff. This is crap. Many taco trucks serve reheated rubbish.
Oh - and the Oaxacan truck at Rose/Lincoln (from 6:30 PM on) makes a mean torta. Good milenesa torta (breaded, spiced, fried steak), excellent lengua torta. Al pastor, carne asada, and chorizo are all crap here, though.
Where else for fine tortas?
(Best I've had was at a truck parked at - 2nd? and Western, by a car wash. Out of cemitas poblanas, but had an awesome carne asada torta).