Heat the olive oil in a large Dutch oven over medium heat. Once shimmering, add the chicken thighs skin side down and brown for about 5-7 minutes until the skin is golden and crispy. Flip and cook for an additional 3-4 minutes. Remove and set aside.
Add sliced fennel and minced garlic to the same pot. Sauté for 3-4 minutes until the fennel is translucent and fragrant with a slight crunch. Stir occasionally, listening for the garlic to become fragrant but not browned.
Sprinkle the turmeric powder over the fennel and garlic, stirring well to coat everything evenly. Let the spices toast for about 30 seconds until aromatic.
Pour in the fresh orange juice and chicken broth, using a spoon to scrape up any browned bits from the bottom of the pot. Bring the liquid to a gentle simmer.
Return the browned chicken thighs to the pot, nestling them into the citrus and fennel mixture. Add lemon and orange slices on top. Cover the pot and reduce the heat to low.
Let the chicken braise gently for about 30-40 minutes, until the meat is tender and falling off the bone, and the citrus is softening and releasing its bright aroma.
Remove the lid, and turn up the heat slightly. Simmer for another 5 minutes to reduce the sauce slightly, stirring gently so the chicken stays intact. The sauce should be glossy and flavorful.
Season with salt and pepper to taste. Carefully arrange the chicken on a serving platter, spooning the citrus and fennel sauce over the top. Garnish with additional citrus slices if desired.
Serve hot, with the fragrant sauce spooned over the tender chicken and a side of your choice. Enjoy the bright, aromatic flavors of this citrus-infused braised chicken.