The piece of meat you see in the picture above is called Picanha. It is cut off the rump of the ox, from what is known as the rumpsteak. If it weighs more than 1.5 Kg, it is probably not all picanha, and has some rumpsteak attached. Known as a tri-tip steak in the U.S. and Canada, it is the most consumed cut in Brazilian churrascarias.
Unlike Argentina and the U.S. and Europe, Brazilians prefer their meat fresh, not aged, and seasoned only with coarse salt. (the one in the picture seems to have been seasoned with pepper, but that is not done) Aged meat is found in Brazil, but fresh is by far the most popular. The preferred state of doneness is very rare, but with the fat crisped. It is quite an art to gril one of these properly. Picanha is normally grilled over charcoal (sometimes gas) in one piece, on a rotating skewer, brought to the table on a skewer, then sliced with the grain in very thin slices. On the plate it is cut acroos the grain, so it has a tender, unusual taste. You can shoose exactly where you want the server to slice from. This means you can get a piece with crust on one side, or no crust - lots of fat or no fat. A delicious and worthwhile experience.
I had to post this picture, which is from the in-flight magazine of GOL, a Brazilian airline. It is a perfect example of good Brazilian grilling.