1 1/2 pounds bone-in, skin-on chicken thighs and drumsticks
1 1/4 pounds Yukon Gold potatoes, peeled and cut into 1 by 1/2-inch chunks
3 teaspoons kosher salt
3/4 teaspoon freshly ground black pepper
2 tablespoons harissa
1/2 teaspoon ground cumin
4 1/2 tablespoons extra-virgin olive oil, plus more as needed
2 leeks, white and light green parts, halved lengthwise, rinsed, and thinly sliced into half-moons
1/2 teaspoon grated lemon zest
1/3 cup plain yogurt, preferably whole-milk (if using Greek, thin it down with a little milk to make it drizzle-able
1 small garlic clove
1 cup mixed soft fresh herbs such as dill, parsley, mint, and/or cilantro leaves
Fresh lemon juice, as needed
Combine the chicken and potatoes in a large bowl. Season them with 2 1/2 teaspoons of the salt and 1/2 teaspoon of the pepper.
In a small bowl, whisk together the harissa, cumin, and 3 tablespoons of the olive oil. Pour this mixture over the chicken and potatoes, and toss to combine. Let it stand at room temperature for 30 minutes.
Meanwhile, in a medium bowl, combine the leeks, lemon zest, ¼ teaspoon of the salt, and the remaining 1 1/2 tablespoons olive oil.
Heat the oven to 425°F.
Arrange the chicken and potatoes in a single layer on a large rimmed baking sheet, and roast for 20 minutes. Then toss the potatoes lightly, and scatter the leeks over the baking sheet.
Roast until the chicken is cooked through and everything is golden and slightly crisped, 20 to 25 minutes longer.
While the chicken cooks, place the yogurt in a small bowl. Grate the garlic clove over the yogurt, and season with the remaining ¼ teaspoon salt and 1/4 teaspoon pepper.
Spoon the yogurt over the chicken and vegetables in the baking sheet (or you can transfer everything to a platter if you want to be fancy about it).
Scatter the herbs over the yogurt, drizzle some olive oil and lemon juice over the top, and serve.