I will be doing pulled/shredded pork in the oven for a party and I'm using a different cut than normal. It's very lean, a sirloin tip roast.

4 separate roasts in one big pan, average of 2.5 lb each.

Do you set cook time by the total weight of the meat, or the average of each chunk? I was going to do 225 for 10 hours (an hour per pound total). Does this sound right? It seems a little long to me is all.

You should smoke it.
Low temp long cook time = tender meat.
I would cook according to size per chunk.At 225. max
The use of a temp probe and it will come out perfect.
One probe in the smallest roast.
Cook each peace of meat like it is, separate.

Don't have the capability to smoke it unfortunately. In the oven it will have to go.

Feeding a group of people tomorrow and I'm having to work the morning half of the day so I will have to do them all at once. Three hours at 225 seems a little short, 10-12 seems too long.  But on the other hand, I'm here for advice and you've been gracious enough to oblige. Thank you. Best I can do I think is put it in early and have my wife stick it with the thermometer after three hours and see where it is. Push comes to shove, if it finishes early we can always put the shredded pork back in the oven to warm.

Usually, time is set by the largest piece of meat.



Put a little space in between the roasts, they should cook about as long it would take only the largest roast if it were by itself (maybe a tad longer - keep an eye / thermometer on it).



I hope that makes sense.  



 

Yes it does make sense. The meat is out of the fridge and about to go in the oven. I will let you guys know how it turns out.

I'd keep them separated and pull them out as they get done. Don't use the total mass of them meat in your calculations b/c cooking involves surface area thats absorbing heat to mass. For example, a 5 pound meatloaf would take more time than 10 half pound hamburger patties, especially if they were thin.

Also, if its very lean, you need to be wary of overcooking it. I'd have recommended brining it if I'd seen this earlier.

Cook time is arbitrary, there are just too many factors. Just set them at the temp of your choosing and check after 3 hours or so, once it starts softening check every half hour 'till its the way you like it. Also every time you check it take the time to baste it. Finish off with a broil un covered to put on some caramelization but be careful with broil because its easy to burn. Happy cooking, its gonna turn out great.

I put all four in together at 4:30 this morning when I went to work. Straight from the fridge to the oven. I pulled them out at 2:30 this afternoon (10 hours) after I got home. Wrapped and let them rest for an hour while we got everything else together, shredded by hand. Delicious! The top half was just a tad on the dry side, I will baste next time to try and help with that but it turned out great for such a lean cut.

I think I'm gonna have to get a Traeger for next time. I know it's sacreligious, but I just can't babysit the food like I used to.

I will also pull the foil and get the broiler going for a better crust in the future. I will say one thing for certain, the meat thermometer is quickly replacing my timer as a cooking tool. Remember, I'm a layman.