Since I have returned from France, I have been writing about the faux-fillet, which is the cut of meat that is traditionally served with Steak-Frites. This has led some curious types (thanks, Robin) to ask me what the faux fillet actually is. Contrary to its sound, it is not a big pile of eggplant and tofu. The faux fillet is actually part of the sirloin,
near the bottom of the cut. It is known in the US as a tri-tip. It can be grilled, chopped or slow cooked. They tend to be much cheaper than other parts of the sirloin. The steaks are as good as any other piece of sirloin, if not better, but they are on the smaller side. That is one reason they make the perfect 10 ounce steak-frite steak. Wikipedia has a review on this, too.