I lived in the city for over a year and I was a regular at this restobar. Even though its a bit hard to get there there by metro (plaza egaña), you can just take the micro (cant remember the name, but theres a station close) to plaza ñuñoa. The food was delicious and they had bunch of different good drinks. If you go during happy hours you get one of the best deals in the city, good drinks for a really fair price.
Extra tip: try the red wine rissotto and the cosmo