Preheat the oven to 400oF (204oC). Season the chicken thighs with garlic powder and half of the salt.
In a large cast-iron skillet or oven-safe pan, heat the oil over medium-high heat. Brown the seasoned chicken thighs starting with skin-side down for 5 to 7 minutes then flip and brown the other side for another 3 to 5 minutes. Transfer the browned chicken to a plate. It won’t be cooked through yet.
Reduce the heat to medium and to the same pan add the fennel, mushrooms, green beans and onion. Cook, stirring frequently, for about 5 minutes or until the onion begins to soften. Add the thyme and remaining salt to the pan and stir to combine. Add the water to the pan and scrape any brown bits away from the bottom of the pan. Stir in the orange juice.
Place the browned chicken on top of the fennel and onions in the pan and bake in the oven for 10 to 15 minutes, or until the chicken is cooked through and the fennel and onions are tender. Divide between plates and enjoy!