Mix all dry and wet ingredients into a suitable mixing bowl and stir well.
Rinse and pat dry chicken.
Place chicken in to a large bowl then pour marinade over chicken. Rub marinade over the entire chicken as well as place some into the cavity of and under the skin. Cover and set in the fridge for an hour to overnight.
Slow roast the chicken at 250 F in the oven for 3 hours, uncovered. After an hour or so, tilt the chicken to let accumulated juices out of the cavity and baste the chicken with the juices.
Repeat this every 30 to 40 minutes while the chicken is roasting.
After roasting, remove cooked chicken from pan leaving the juices behind.
Strain the liquid and pour into small sauce pan over medium heat. Add to that ½ cup chicken stock and stir.
Make corn starch slurry by mixing the corn starch with about 2 tbsp water. Pour slurry into gravy to thicken slightly if desired. Otherwise, reduce the sauce over 15 minutes or until the desired consistency is reached.
Carve chicken on a platter and serve with gravy and steamed rice.