This is another recipe found for ZWT Event from Steven Raichlen's "The Barbecue Bible". This is what he states in the intro: Matambre (literally, "hunger killer") refers both to a cut of meat and to the series of dishes that are made from it. The cut, which doesn’t exist in North America, is a large, 1/2-inch-thick rectangular muscle from the chest of the cow. Tough but flavorful, matambre is always served well done: the prolonged cooking helps break down the tough meat fibers.
The simplest version of matambre-the one served as an appetizer at estancias (ranches) and steak houses in Argentina-consists of the flat piece of the meat sprinkled with spices, grilled, and cut into 1-inch squares to be served on toothpicks. To re-create it in North America, I like to use skirt steak. Skirt steak is a smaller cut than matambre, but the thinness and muscle structure are similar. Skirt steak is more tender, however, so you don’t need to cook it as long.
NOTE: Need to allow at least 4 hours to marinade but overnight is best.