Tango Sur is a great little restaurant on Southport, just south of Grace. It's always packed with large groups, so it's a good idea to get there early! We actually tried to eat there several times before we finally got a table!
The menu is mostly meat, but it has a great variety of Argentinian beef dishes. The portions are large, so you can take some home for another meal! We definitely didn't leave hungry!
It's a great restaurant for a birthday or other celebration and they do their best to accommodate larger groups. Give it a try, you'll be glad you did!