Heat the oil in a skillet over medium high heat.

Season the chicken with salt and pepper to taste.

Add the chicken to the skillet, and cook for about 5 minutes on each side. Remove, and set aside.

Pour all but 1 tablespoon of the drippings from the skillet.

Add the onion to the skillet, and saute until beginning to soften.

Stir in the mushrooms, and saute until softened.

Mix in the garlic, Italian seasoning, red pepper flakes if you are using and tomato paste, stirring to combine for 30 seconds.

Deglaze the skillet with the white cooking wine.

Pour the diced tomatoes into the skillet, and stir to combine well.

Mix in the capers, and add the chicken back to the skillet.

Simmer until the chicken is fully cooked through.