Preheat your oven to 400°F (200°C). In a small bowl, combine the smoked paprika, garlic powder, onion powder, oregano, salt, and pepper. Pat the chicken thighs dry and season both sides with about half of the spice mixture.
Heat 2 tablespoons of oil in a Dutch oven over medium-high heat. Once the oil is shimmering, add the chicken thighs and sear for 2-3 minutes per side until golden brown. The chicken will not be cooked through. Transfer the seared chicken to a plate.
Reduce the heat to medium and add the remaining 1 tablespoon of oil to the Dutch oven. Add the chopped onion and cook for 3-4 minutes, until softened. Add the minced garlic and cook for another minute until fragrant.
Stir in the uncooked rice, toasting it lightly for about a minute. Pour in the chicken broth and scrape up any browned bits from the bottom of the pot.
Add the frozen vegetables and the remaining spice mixture to the pot. Stir everything together to combine.
Nestle the seared chicken thighs on top of the rice and vegetable mixture. Bring the liquid to a gentle simmer on the stovetop.
Cover the Dutch oven with its lid and carefully transfer it to the preheated oven. Bake for 35-40 minutes, or until the liquid is absorbed and the rice is tender.
Check that the chicken is cooked through. An instant-read thermometer inserted into the thickest part of a thigh should register 165°F (74°C).
Let the dish rest, covered, for 5 minutes before fluffing the rice with a fork and serving.