Season the chicken breasts on each side with Italian seasoning, salt and pepper.
Heat the olive oil in a large sauté pan. Then brown both sides of the seasoned breasts in the olive oil and remove from heat.
Add wine to the pan and simmer for two minutes, then and add the garlic, onion. Sauté until onions are tender.
Add tomatoes and all but 2 tablespoons of the chicken stock.
Bring to a gentle boil and return the chicken breasts to the pan.
Reduce heat and simmer until chicken is done, 10 to 15 minutes.
Thicken with remaining chicken stock and cornstarch, if needed.
Season with salt and pepper to taste. Serve over rice or pasta.