You should not cover this lamb roast because it will come out over cooked and not roasted. To avoid mess in the oven use a Dutch oven or roasting pan with high walls. No mess.

Not covering it makes a great mess in oven. I made this for my gf and she asked me to cover 3 times I said. It’s not what it says…
It turned out good but…damm I looked like an idiot.

Hi Diane. The times per pound are pretty accurate but again all ovens vary, even brand new ones. I have 2 brand new ovens in the studio and in the house kitchen and they do bake differently. So it’s best to undercook the roast a bit and check with a knife for doneness. You are on the right track of thought. Good luck!

Sure!

The second option. You add veggies 35 minutes before the roast is done, so they cook together.

So just for me to understand, do you wait until the end cook time of the roast and then start roasting the veggies, or do you estimate 35 mins before the end of meat cook time and add the veggies in the same pan so that the meat and veggies are cooked together?

If I understand your question correctly, if you pre-cook potatoes I would add them 20ish minutes before the end cook time.