Argentinian restaurant in Bergen County?
The only Argentine restaurant I know of is La Fusta in North Bergen, Hudson County. It's easily accessible off the New Jersey Turnpike extension 16E heading towards the Lincoln Tunnel. You would exit on Route 1 & 9 South and take the first U-Turn jug handle.
1110 Tonnelle Ave., North Bergen, NJ, 07047
Although I have have never been, One of my employees used to go there on regular occasion and that's how I am aware of it. He used to invite me to have dinner there, but I never made it. From what I understand, they have excellent steaks and meat platters to share.
I'm not sure if this style of food is Argentinian or Portuguese but there is a new restaurant in Ridgewood "The Stable" which according to the Record the chef owner build to resemble his homeland of Argentina. They offer among other things a rodizio option of all different kinds of grilled meats like the Portugese restaurants in the Iron Bound section of Newark. They also offer charcoal grilled steaks, chops, chicken...ect. I haven't been yet but planning to go soon. I believe they just opened in November.