Preheat your oven to 400 °F. You’ll be using bottom rack of your oven.
Prepare your lamb shoulder by trimming away any excess fat. Place your lamb in the center of a large roasting pan, one which is just large enough to hold the lamb and all of the potatoes.
4-5 pounds lamb shoulder
Pour 1/4 cup freshly squeezed lemon juice over your lamb shoulder and then sprinkle your lamb evenly with 1 tablespoon salt, 1 teaspoon ground black pepper, and 1 tablespoon Greek oregano.
1/2 cup lemon juice, freshly squeezed, divided, 2 tbsp dried Greek oregano, divided, 1 teaspoon ground pepper, 1½ tbsp salt
Peel your potatoes and cut them into thick wedges (for small to medium sized potatoes, cut them in quarters, and for larger potatoes, cut them into 6 wedges).
10-14 medium sized potatoes
Place your potatoes into the roasting pan, surrounding the lamb. Pour 1/4 cup freshly squeezed lemon juice over your potatoes. Evenly sprinkle your potatoes with 3/4 teaspoon salt, and 1 tablespoon oregano.
Pour the olive oil and vegetable oil over your lamb and potatoes.
1/4 cup Greek olive oil, 1 ¾ cups vegetable oil
Place your roasting pan on the bottom rack of your oven, uncovered. Cook for 1 hour and 30 minutes. Remove roasting pan from oven and sprinkle 1 teaspoon of paprika over the potatoes. Turn your lamb shoulder over. Cover the lamb loosely with aluminum foil. Leave the potatoes uncovered.
1 teaspoon paprika
Return to oven and cook for an additional 45 minutes. Check your potatoes for doneness. They should be soft and golden yellow.
Allow your lamb to rest for 5 – 10 minutes before carving, to allow juices to settle.
Enjoy!