La Casona del Molino

This is a peña that local Argentinians go to. A peña is like an Argentinian version of an open mike night (and way better too than the Aust version i know) + restaurant. They know music and sound amazing doing it and some how every argentinian in the restaurant knows all the words to all of the songs that are played. So basically patrons bring their guitars, drums, panpipes, whatever and play and sing you amazing music whilst you eat delicious, perfectly cooked meats.
So in terms of the restaurant part of this place, I highly recommend sharing a meat «grill» for two between three or four instead. Definitely try all of the empinada flavours and try the grill with a salad. There is a semi scary hot chip dish with cheese on it which may or may not cause a heart attack which I would probably stay clear of but if you are into that kind of thing it is in small doses tasty. The wine is cheap, the beer is cheaper and the staff are really relaxed and cool. You can book or otherwise turn up at 10pm to be safe and snag a table.
The building is like a converted home, really colourful and chilled out. There is three main inside rooms and a big outdoor area that all turn into different musical sections after about midnight. This place is open until 5am and around 4am you will start wondering why the place is still full of locals when it is a thursday (does anyone work?).
GO here. Talk to the locals (spanish only really). Plan on a 5am-​er. There are taxis waiting for you at the end of the night.