Pre-heat oven to 180°C/350°F. Finely chop onion and garlic. Transfer to a bowl and set aside. Thinly slice red and green bell peppers, mushrooms and celery. Add to bowl. Remove thyme and rosemary leaves from stems, add sage and finely chop herbs together and set aside.
Heat oil in an ovenproof pan over medium-high heat and sear chicken breasts on both sides. Add salt and pepper to taste. Remove chicken from pan and set them aside. Add onion, garlic, and vegetables and sauté for approx. 3 min.
Add bay leaves and tomato paste and stir to combine. Add olives, then deglaze the pan with red wine. Add the canned tomatoes, then fill the tomato can about halfway with water and add to the pan. Add herbs. Nestle chicken back into the pan, covering with sauce. Season with salt and pepper.
Put the pan in the pre-heated oven and bake at 180°C/350°F uncovered for approx. 30 min. Enjoy with crusty bread!