Grind together the garlic, mustard, salt, oregano, pepper and thyme until the garlic is completely mashed. Add the juice of the lemons and the olive oil and mix well.
Wash and salt the cavity of the chicken and place the juiced lemon halves into the body. Massage, or rub the oil/lemon/spice mixture over the chicken to coat.
Place the chicken on a small grill in a large pan and surround it with the potatoes. Pour the remaining mixture over the potatoes and pour the water into the pan. (Use enough water to almost half-submerge the potatoes)
Bake at 350°F or 180°C, basting often with the juices from the pan and turning the potatoes as required.
Cooking time 1½ - 2 hours until the juices from the chicken run clear and the internal temperature reaches 190°F or 87°C.