I know you want Argentinian, but I personally don't know of any Argentinian restaurants around here..so as an alternative, a better alternative if you ask me

are Brazilian steak houses.
The Brazilian steak houses which are now as famous as David Beckham around here serve the traditional Brazilian barbeque of the Gaucho style. Of course the Gaucho culture encomposses not only Southern Brazil but Uruguay and Argentina!
So the delicous steaks served up at those places would probably fit your bill. The best are Fogo de Chao and Rafain's, both in Addison. Fogo is on Midway/Beltline and Rafain's is on Frankford/Tollway on the Northbound side.
There is also Texas de Brazil, just up the street from Fogo, and Boi na Braza out in Grapevine. Those two are also good but don't stack up to Fogo or Rafain's.
Also, there is some authentic Brazilian food to be found at a place called Brazil Brasileiro in Richardson off of Arapaho and Custer. They serve up some amazingly great food ranging from steaks, fish, lasagna, rice, beans, salads, deserts, and more all prepared in the Brazilian style which is full of flavor. You put as much food on your plate as you want then you weigh it! You pay by the pound.
I highly reccomend this jewel. All the DFW area Brazilians eat there so you know it has to be good...plus every night there is a live band/person playing soothing bossanova as you eat. Can't get any better
FYI: There is a place in downtown where you can buy authentic Picanha meat from Argentina and Brazil to throw down on the grill...don't ask me how they get it because I would love to know myself. I forget their name but as soon as I remember or find out I'll let you know
