Heat the olive oil in a large skillet or Dutch oven over medium-high heat until shimmering. Add the chicken thighs, skin side down, and cook, without moving, until golden brown, about 5-7 minutes. Flip and brown the other side for another 5 minutes. Remove the chicken and set aside.
Add sliced onion and minced garlic to the same skillet. Sauté until the onion is translucent and fragrant, about 3-4 minutes. Stir in paprika and cinnamon, cooking for another minute until spices are aromatic.
Pour in chicken broth and lemon juice, scraping any browned bits from the bottom of the pan with a wooden spatula. Bring the mixture to a simmer, then return the browned chicken thighs to the skillet, skin side up.
Reduce heat to low, cover, and simmer gently for 25-30 minutes, until the chicken is cooked through and tender. The sauce should thicken slightly and coat the chicken pieces evenly.
Uncover and increase heat slightly if needed to thicken the sauce further. Check for seasoning and adjust lemon or spices as desired. Serve the chicken with the sauce spooned over, garnished with fresh herbs if available.