Season the chicken thighs with salt and pepper. Heat olive oil in a skillet over medium-high heat. Cook chicken skin-side down for 5-7 minutes until golden brown, then flip and cook for another 5 minutes. Remove and set aside.
In the same skillet, cook the sliced Italian sausage for about 5 minutes until browned. Remove and set aside with the chicken.
Add diced onion, minced garlic, and sliced bell peppers to the skillet. Sauté for 4-5 minutes until softened. Stir in oregano, thyme, and red pepper flakes, cooking for an additional minute.
Pour in chicken broth, white wine, and apple cider vinegar. Stir to combine and scrape any browned bits from the skillet.
Return the chicken and sausage to the skillet, nestling them into the sauce. Bring to a simmer, cover, and reduce heat to low. Cook for 30-35 minutes until chicken is tender.
Taste the sauce and adjust seasoning with salt and pepper. Garnish with chopped parsley before serving.