I've had this twice now, once at a Brazilian place and the other time a Colombian place.
Its comes in a container like tartar sauce would. Its very vinegary, and there is minced onion, tomatoes, possibly peppers too I can't recall. Its not like a salsa where it has some body to it, it looked like basically vinegar with minced veggies. Both times it was served with a grilled chicken & steak plate.
I want to know if anybody knows what this is called, and possibly how to make it. I'm trying to eat healthy so grilled chicken breasts would be great but I never have anything to put on them. I could eat this stuff everyday.