Everything I can find calls for a two-pound roast, but I have a five-pound roast. Everything I can find also says to cook it at 350° F for one hour. I may be wrong, but this doesn’t seem nearly long enough. On top of that, I can’t find the meat thermometer anywhere, further compounding the problem. So how long and what temperature for a five-pound boneless roast? Also, I don’t have much in the way of seasoning. Would a little salt, pepper, and rosemary do the trick nicely? Or maybe I should run to the store and get some garlic powder? Any advice would be appreciated here, thanks in advance.
What cut? Loin?
Salt and pepper at a minimum. Or make a dry rub. For example:
1 tablespoon cumin
1 tablespoon paprika
1 tablespoon granulated garlic
1 tablespoon granulated onion
1 tablespoon chili powder
1 tablespoon brown sugar
2 tablespoons kosher salt
1 teaspoon cayenne pepper
1 teaspoon black pepper
Cover and put into a 225°F oven for about six hours or so. Serve with BBQ sauce on the side.
Boneless pork sirloin roast, if that helps.
Don’t know if I’ve ever roasted pork at that high a temp for that short of time.
When I do a 7-8 lb pernil (pork shoulder) at 300 degrees it takes about six hours, so that does sound slightly dicey.
2 hours at 325 degrees.
But, next time locate your meat thermometer before starting. Makes life much better.
Yeah, With pork I would double check for any other thermometer option(maybe the store you were going to run too has a cheap one?). Over-shooting by 4-5 degrees can turn an awesome roast into dry and disappointing.
The problem is getting the heat to the center of the roast.
If quick is the way you want to go, cut it in half then lay each piece cut side down. The cut inch deep slits on top of each piece. (I like to insert garlic cloves in those slits.)
Then 350 for about 2hrs.
For a 2-pound loin roast, an hour at 350 seems just about right to me. Perhaps even a tad long, but the thermometer would be your best friend here.
samclem’s suggest sounds about right to me for a 5-pound sirloin roast. I’d expect somewhere around 2 hours at 350.
This isn’t pork shoulder where you’re going for 225-300 for half/whole day type cooking. Loin and sirloin are leaner cuts with not as much connective tissue, so I aim for about 150F internal rather than something closer to 200 with shoulder.
When you find your meat thermometer, the USDA now recommends an internal temp of 145 with a 3 minute rest:
As mentioned, that’s the difference between a dry, ok roast at 165 degrees and a delicious, juicy roast. When I started cooking pork loins at 145 (I actually went 140, cuz that should kill most everything) it was like wow, I didn’t know a pork roast could be this good. If you go by just cooking time you’ll err on the side of overdone.
I also came to suggest low and slow.
Low and slow with a sear at the end also works for pork sirloin. Difference is just the final temperature one is aiming for. With cuts rich in collagen, like a pork shoulder, you want to get that puppy between 195 and 205, and you want it to hold at 170+ for as long as you can. With a lean sirloin, 145 tops.
Yes, sure. I didn’t mean to imply otherwise.The temp is what you’re aiming for. The main benefit of doing a loin low and slow for a lean cut is that you get more even cooking throughout. (But I typically do roast at 350 for stuff like this.)
Does no one else start high, end low?
I like to zap a loin roast at 450 in a preheated oven for about ten minutes, then lower to 325-350 to finish it. The exterior comes out nice and crackly.
It’s also nice to forego the rack and lay the meat on a bed of sliced onion and garlic in the bottom of the roasting pan.
I bought a four-pound SHOULDER roast yesterday. That baby’s going to get it low and slow, maybe 225, and all day, with an occasional vinegar mop. Then get shredded and served on a roll. It’s not real barbecue, but it’s awfully good.
That’s the traditional approach for roasts, but I prefer the reverse method (the meat dries out a bit while you’re cooking it so you get a better sear, plus you have a more even doneness on the inside, that is, if you prefer your pork cooked to 145 or so.)
And, no shocker, but it looks Serious Eats has actually covered this in regards to pork. (I’ve only seen the prime rib recipe for this method. I can’t remember where I first learned it. I know Alton has mentioned it on his show, but it’s also been in Cook’s Illustrated. It was somewhere around ten to twelve years ago I first came across it and started doing it.) Looks like that recipe has a loin roast at 250 for about two hours (bringing internal to 140) and then 10 minutes at 500 to crisp it up (after letting it rest.) For a sirloin roast, it’ll be a little longer, since (at least the ones I see at my supermarket) they’re thicker and shaped differently than a loin. But there’s a lot of variation. Wish you had that thermometer. 
Thermometer: I have a 20-year-old GE gas stove with a probe attachment. You jam that sucker into the roast, then connect it to a socket inside the oven. You set the oven to the temp you want the roast to end up at, then enter the heat level. It reads LO until the roast hits 100 degrees, then tracks the increase for you so you can busy yourself with the veggies and salads and whatnot.
It’s magic. I haven’t spoiled a roast in ages. Very handy around Christmas time, when everyone wants a standing rib roast of beef, which can cost over a hundred bucks.
Don’t try and make pulled pork out of a loin, and don’t try and make a loin out of a butt or a butt. I know this from many years of terrible attempts at “lean” pulled pork that was a chewy mess. Loin 140 deg. everything else low and slow.
Agreed, I stand corrected, good advice
My GE oven isn’t quite as old, and it has the same attachment. Unfortunately I’ve lost the probe. I use my BBQ thermometer, which measures both oven temp and meat temp and has a wireless receiver, which I love for long cooks.
pulykamell said everything I would regarding hi to low versus low to hi. Low to hi leaves more meat at the desired doneness. I do sometimes roast chicken hi to low, starting at 500 (my oven’s hottest temp) for 15 minutes, then 170 (my oven’s lowest temp) until done, using convection.