Pat chicken thighs dry with paper towels. On a large plate, sprinkle chicken all over with 2 teaspoons kosher salt. For better salt penetration, let chicken sit at room temperature for 30 minutes or uncovered in the refrigerator for up to 8 hours (optional).

In a large stainless steel skillet, heat oil over medium-high heat until shimmering. Add chicken thighs, skin-side down, and cook until skin is golden brown, 5 to 7 minutes, lowering heat if skillet starts to get smoky. Transfer chicken to a large plate and set aside.

Reduce heat to medium. Add onions and cook, stirring occasionally, until softened and lightly golden, about 7 minutes.

Add garlic, turmeric, paprika, ginger, black pepper, and 1 ¼ teaspoon kosher salt, and cook, stirring and scraping up browned bits, until very fragrant, 1 to 2 minutes.

Add rice, cilantro, preserved lemon, and broth, and stir to combine.

Nestle chicken into broth, skin-side up, adding any accumulated liquid. Bring to a simmer, then reduce heat to low, and cook, covered, until rice is tender, liquid is mostly absorbed, and chicken is cooked through and tender, registering 175°F (79°C) to 195°F (91°C) with an instant-read thermometer, about 20 minutes.

Off heat, let rest, covered, until rice is fully tender and all liquid is absorbed, about 10 minutes.

For the Sauce: Meanwhile, in a small bowl, whisk oil, cilantro, and preserved lemon until well combined. Season with salt and pepper to taste. Set aside.

To Serve: Drizzle sauce over rice and chicken and top dish with additional cilantro.