Make this, and you'll never be satisfied with a roast beef sandwich in a deli
ever again, I promise. you'll also find that you've become dissatisfied with the state of prepared cold cuts in general. Cooking is much like drinking tequila
- once you try the good stuff, everything else tastes like cardboard.
Unless you, um, like that sort of thing. Anyway.
There are hundreds of ways to cook a roast, but this is my favorite. The advantage to this particular way is that it requires little to no work, can be used on any cut of roast and, when finished and sliced and nicely dressed, makes the best roast beef sandwiches I've ever had. You can plate it with veggies and potatoes and gravy if you've the mind to and it's awesome (and I'll get to noding that eventually), but in sandwiches, it excels.
I'm not even gonna bother with an ingredient list because it'd be laughably short, so. Here's the plan:
Set your oven to 375F. While that's warming up, take your roast and cut eight holes in the top where the fat lives. Stuff those holes with slivers of garlic. Then rub the beef down with olive oil - the oil will brown the outside nicely and give the spices something to stick to. Rub every inch of the outside of the fucker with salt, pepper, and fresh thyme. Fresh thyme - the stuff costs fifty cents for a huge handful and it'll last you ages and the dried stuff burns in the oven, so avoid it.
Put the roast directly on the oven rack with a pan underneath to catch the drippings, with the fat side of the roast facing up. You can cook it in a pan, too, which is better if you're making veggies with it that you want commingling with its juices and whatnot, but doing it this way takes a lot of the fuss out of turning it (real men cook with...convection?) and you'll get a more tender roast this way because gravity's a wonderful thing - as it cooks, the fat will drip down through the meat and keep it moist.
Cook the roast for thirty to thirty-five minutes on 375F - this'll brown the outside and make the rind all nice and crispy. Then turn the heat down to 225F.
I've never been a big fan of meat thermometers (beef is usually done when it smells right, y'know?) but for this, it's necessary. Cook the roast until its core temperature is around 135 - 140 degrees. This'll give you a nice, pinkish but not bloody, roast. Depending on the size and fattiness of your roast, this will take between an hour and two. Pull it out of the oven and put it on a board. Let it sit for 15 minutes or so.
Now. Slice that bitch, as thin as you can. You can get cheap deli slicers designed for a home kitchen, but if your kitchen is anything like mine you have a hard enough time storing the basics without some ungainly diabolical machine hogging all the counter space. Use a very, very sharp knife, (watch your fingers!) and let it sit for 45 minutes or so to let the slices cool down. You can throw it in a plastic bag in the fridge if you're in a rush, but I wouldn't - ideally, this stuff should be eaten at room temperature and the most hassle-free to assure that state is to, you know, leave it in a room for a bit.
Once it's cooled down some, make your sandwiches. You can make them any way you want of course, but do me a favor and try it my way first. The trick is to not mask the taste of the meat with unnecessary condiments and toppings - you want just enough extra stuff to compliment and moisten the meat without overpowering it. To that end, put a few slices of beef on fresh (seeded) rye bread with a moderate amount of mayo (or, for kick, some of that creamed horseradish sandwich spread. Using pure horseradish is a bad, bad idea) fresh sliced red onion, and salt and pepper.
A quick note on the bread: there's a bit of an art to this. If the beef is room temperature, you definitely want a more flavorful and heartier bread as blood's gonna be dripping everywhere and you'll need something substantial to sop it up. Once it's cold, though, that bread makes the sandwiches drier than you'd want and you'd be better off with potato bread. It's not that big of a deal, really, but we're striving for perfection here, so.
A three pound roast is good for about five sandwiches or so, more if you're stingy but really, what's the point?