In an ovenproof skillet or baking dish, whisk together 2 tbsp minced garlic, 2 tbsp vegetable oil, 2 tbsp Dijon mustard, the zest of 2 lemons, and the juice of 1 lemon until combined.
Add the 4 chicken thighs to the marinade and coat both sides thoroughly.
Remove the chicken from the skillet and place on a plate; cover and refrigerate for at least 30 minutes to marinate.
Preheat the oven to 350°F (175°C).
In the same ovenproof skillet or baking dish, add 1½ cups white rice and 3 cups water or chicken broth; whisk to combine with any remaining marinade so the rice is evenly distributed.
Return the marinated chicken thighs to the skillet, nestling them on top of the rice. Season generously with salt, black pepper, and paprika.
Bake uncovered for about 40 minutes, or until the rice has absorbed all liquid and the chicken reaches 165°F (74°C) at its thickest point. Timing may vary by rice type and chicken thickness.
Optional: Heat a skillet on high and sear a few lemon slices until charred, then use as a garnish.
Let rest a few minutes, then serve the chicken over the rice topped with charred lemon slices if using.
