Pat the chicken thighs dry with paper towels and season both sides with salt and black pepper.
Season the beef cubes with salt and black pepper.
Heat 1 tablespoon of olive oil in a large heavy-bottomed skillet or Dutch oven over medium-high heat.
Add the chicken thighs skin side down and brown for about 5-6 minutes until golden and crisp. Flip and brown the other side for 4-5 minutes. Remove chicken and set aside.
Add the beef cubes to the same skillet and brown on all sides for about 6-8 minutes. Remove beef and set aside with the chicken.
Add the remaining 1 tablespoon of olive oil to the skillet. Add the sliced onion and bell peppers and sauté for 5 minutes until softened.
Add the minced garlic and cook for 1 minute until fragrant.
Pour in the red wine, scraping the bottom of the pan to deglaze and loosen browned bits. Simmer for 3 minutes until slightly reduced.
Stir in the crushed tomatoes, beef broth, dried oregano, dried basil, dried thyme, crushed red pepper flakes, and bay leaves. Season with salt and black pepper to taste.
Return the browned chicken thighs and beef cubes to the skillet, nestling them into the sauce.
Bring the sauce to a gentle simmer, then reduce heat to low. Cover and cook for 1 hour, stirring occasionally, until the meat is tender and the sauce has thickened.
Remove bay leaves. Taste and adjust seasoning with salt and pepper if needed.
Sprinkle chopped fresh parsley over the top before serving.