Preheat oven to 400F.
Season chicken on both sides with salt and pepper.
In a non-stick skillet, heat oil on medium-high heat.
Dredge chicken in flour then brown in the skillet 5 minutes each side starting skin side down first the flip. Remove chicken and set aside.
In the same skillet add mushrooms and cook for two minutes.
Add onions and let it cook for 1 minutes.
Add Garlic for 30 seconds then add the peppers stirring everything together for another 30 seconds.
Add a pinch of salt then turn heat off.
In a 13x9 baking dish mix together crushed tomatoes, chicken stock, vinegar and oregano, capers if using.
Mix in the vegetables then nestle the chicken thighs into the tomato sauce.
Add the green olives if using cover and bake for 25 minutes.
Remove the cover and continue to bake for another 15 minutes until the sauce is bubbly and reduced.
Serve with pasta.