Pit beef is prepared by grilling a beef roast under high heat until it is medium rare, then sliced thin, and eaten on a platter, or as a sandwich with horseradish. Here’s how to make it:
First, the roast. I prefer sirloin tip, although some use top or bottom round. I don’t like the latter due to the thick wedge of fat then runs through it. I’ve heard of people using eye round, but grilled eye round is barely fit for human consumption, so I really can’t suggest that. Don't bother using any fancy cuts. And this is not an application for chuck roast (which is for pot roasts) or brisket. Tri Tip would work great, but good luck finding any here out east. Those dastardly Californians hog it all.
Next, add the spice rub. I use two portions of salt to equal portions of ground red pepper, onion powder, garlic powder, paprika, oregano, and a little ground red pepper. There’s no exact science here.
Coat your entire roast with the rub.
Then put the roast in the fridge at least a day before you’re going to cook it, so the spices can get absorbed into the meat.
Next, take the roast out of the fridge, and let it sit on the counter for an hour or so, to warm up a bit, so when you grill it, you’ll maximize the volume that stays at medium rare. Of course, the USDA food safety police say this is a dangerous food safety violation.
Meanwhile, get your grill going nice and hot, and put the roast on.
Grill with the lid off on high heat.
When your instant read thermometer says 123F, you’re done. That’s medium rare. The USDA says 145F is medium rare. They’re idiots.
Next, you want to tent your beef under aluminum foil, to let it rest, so you don’t lose the juices. Don’t skip this step. If you cut into the roast now, all the juices will come gushing out, and you'll be left with dry meat.
While your beef is resting, you want to slice your onions. I use an electric meat slicer, since I’m going to use it to slice the beef anyway.
Slice your onions thin. As thin as you can.
Slice your beef thin as well. Sure, you can use a knife if you’re good at it and not lazy. Me, I’m lazy. And I have a deli slicer, so I may as well use it.
Serve on a platter. If you want to make a sandwich, Schmidt's 647 bread
http://schmidtbaking.com/products/647-2/ works, I'd suggest toasting it first.
Put some horseradish on the beef and onions. If you’ve got mayonnaise, throw it away now, before someone uses it.