Based on a December posting on this board I went off in search of La Mexicana on White Street. It turned out to be a market and music store, no freshly prepared food. However, just next door at 141 White Street is Pancho's Tacos, and I think that's the place that Wendy J must have meant.
I really enjoyed the pozole, very flavorful broth and plenty of pork and hominy, plus freshly chopped onion and cilantro you could add to taste. Also had a grilled shrimp dish that was very good, and their rice is terrific.
I had been to both Castro's Coffee Shop and Antojitos Mexicanos in Brooklyn (featured in Jim's book) over the past month. I didn't think that the tacos at Panchos were in the same league, though I got them to go and perhaps I was supposed to add lettuce, tomato, etc. at home --- they were stuffed with just the meat.
Still, a good place on balance, and I plan to return.