Preheat oven to 425 degrees F (220 degrees C).

Place meat (if using) directly on the oven rack.

Place a roasting pan on the rack beneath the meat to catch drippings.

Peel potatoes and place them whole in a large saucepan.

Cover potatoes with cold water and bring to a boil.

Simmer for about 5 minutes, then drain.

Shake the potatoes roughly in the colander to bruise their sides.

After the roast has cooked for at least 20 minutes, add potatoes to the drippings in the roasting pan.

Strip the leaves off rosemary sprigs and toss them over the potatoes.

Sprinkle with salt and pepper.

Shake the pan well to coat the potatoes in fat and drippings.

Continue to cook, occasionally turning the meat and shaking the potatoes, for at least another hour and up to about 90 minutes.

Cook until the roast is cooked and the potatoes are crisply golden-brown outside and tender inside.