El Pique and Los Seras are popular local taquerias that are just hitting their stride around 10pm. Not touristy and are super cheap. Both are on 30th Ave. Los Seras is closest to CM on 30th Ave between calle 3 & 5, maybe a 10 minute walk. Go to the right from the CM door, the first right go up calle 5 to 30th, go left one block. El Pique is another 4-5 blocks down 30th, just past Benito Juarez. It's more than a 10 minute walk from CM, probably a taxi ride is in order, but worth it.
I gave you the "simple" directions but google can show you a slightly shorter route.
www.google.com
www.google.com
I can also second Casa Cuzamil.