Brown chicken in oil. Add salt and pepper. Remove from the pan. Add onions to the same pot along with the bell pepper. Saute for 5 minutes. Add the remaining vegetables, curry powder, thyme, cayenne, and salt. Simmer for 10 minutes. Return chicken to the pan. Add tomato sauce. Bring to a simmer and cook for 30 minutes. Add vinegar, stir well and serve over rice or couscous.