I spied this place a few times this past week while traveling on the Belmont bus, a quick search didn't turn up any information, so I stopped in for lunch today to investigate.

I knew that I would order birria, but I saw they also had menudo, so I ordered that, too. Service was friendly, grew even friendlier as I settled in for my lunch, but it took some convincing for them to bring me both dishes. No one behind the counter could believe that I would want to eat both birria and menudo by myself. Behind the counter I heard in Spanish: "That's too much food for her." I interjected that I knew it'd be a lot of food, that it was OK, that I'd take any leftovers
para llevar. Then one of the people behind the counter went to a back room and retrieved a plastic bucket to illustrate how large the serving of menudo would be. (Should have gotten a photo of that. Menudo comes in only one size here--gigantic.) I perservered though, and I was rewarded.
Menudo served piping hot before garnishes:

This was pretty good--big chunks of tripe with a nice consistency and broth that was flavorful but a little too oily. I didn't realize until I overheard another table that I had to ask for my menudo to come
con pata. Some foot would have broken up what eventually was the monotony of a very large bowl of tripe.
Birria:

The birria I thought was good to almost very good--fine goat flavor complimented by a broth not as light or clean as Zaragoza's but still very enjoyable. I sopped it all up with the handmade tortillas, which had a more tissuey texture that I prefer.
The place was basically empty when I arrived and sat down shortly after noon, but by the time I left most of the tables were occupied with people eating either menudo or birria (not both), so I felt like I made the right choices. I don't know this neighborhood, but I don't live too far away. I can definitely see myself making a return visit to El Carmen.
Birrieria y Taqueria El Carmen
4101 W Belmont Ave
Chicago IL 60641
773-283-3178