No recommendation for Feijoada, but checking to see if you need a visa and if so, do you have one, otherwise any recommendation would be pointless as you would need to clear customs. Also with a 12 hour layover, allowing for clearing customs on arrival and then check-in, security, and passport control on departure your 12 hours will dwindle to 9 or 10 at the most depending on time of day. It will dwindle further depending on how bad the notorious Sao Paulo traffic is, again depending on time of day and day of week. So if you can enter Brazil, the only recommendation I can make is don't travel too far from the airport.