Pre-heat oven to 400°F.
Trim off long edges of the russet potatoes so that they can lay flat.
Cut in half, lengthwise, and rinse in a bowl of cold water to remove excess starch.
Pat dry on paper towels.; season generously with black pepper, cayenne, and salt.
Coat the bottom of a large baking dish with olive oil; lay potatoes seasoned-sides down in the dish; brush tops with more olive oil; season with pepper, cayenne, and salt.
Bake, in the pre-heated oven, for 20 minutes.
Remove and carefully flip potatoes over; let rest for 10 minutes.
Meanwhile, in a small bowl, combine broth with lemon zest and juice.
Pour mixture over the potatoes; scrape zest off the tops of the potatoes and back into the broth; stick oregano sprigs between the potatoes; season with pepper; shake the dish lightly to slosh the sauce back and forth.
Return potatoes to the oven and roast for 15 minutes.
Remove from oven; flip again; place back in oven and continue roasting until very soft and creamy on the inside and crusty on the outside, 10 to 15 minutes more.
Remove from oven; flip over once more to serve; drizzle more olive oil on top; sprinkle with pepper and more oregano; serve.
