Start by preheating your oven to 425°F so it's fully hot by the time your pan goes in. While it heats, peel and cut your potatoes into large wedges so they hold their shape during roasting. I also zest and juice my lemons at this point, since it's easier to do before everything else is going.
In a mixing bowl, I combine the olive oil, lemon juice, lemon zest, chicken stock, grated garlic, rosemary, oregano, salt, and pepper. I whisk it until it looks slightly emulsified. This marinade is doing double duty; it flavors everything and becomes your pan sauce later.
I add my chicken thighs and potato wedges directly into the roasting pan, then pour the marinade right over the top. Using my hands, I toss everything together so each piece gets coated evenly. This step matters more than people think for flavor.
I lay the chicken skin-side up and scatter the lemon slices over the potatoes only, never on the chicken. If lemon slices sit on the chicken skin, they trap steam and stop it from browning properly, which is a mistake I made early on.
The tray goes into the oven for 45 to 50 minutes, until the chicken hits an internal temperature of 170°F. Around the 30-minute mark, I baste the tops of the chicken and potatoes with the pan juices using a spoon or brush. This keeps everything glossy and deeply flavored.
Once the chicken is done, I pull it out to rest on a plate so it stays juicy. Then I crank the broiler to high and slide the pan back in on the middle rack for about 5 minutes, just until the potato tops turn golden and slightly caramelized. Watching closely here prevents any burning.
Finally, I arrange the chicken and potatoes on a serving plate, spoon the warm pan sauce over everything, and finish with a generous sprinkle of fresh chopped oregano. That last step of pouring the sauce back over is what makes this dish taste like a restaurant plate.