Remove giblets and neck from chicken. Rinse and pat chicken dry inside and out. Tie chicken legs together with kitchen string; tuck wings under back. Place, breast side up, on rack in roasting pan. Combine mustard, soy sauce, gingerroot and garlic; brush all over chicken. Pour in 1-1/2 cup of the chicken stock. Roast in 325F 160C oven, basting every 30 minutes, for 2 hours or until juices run clear when chicken is pierced and meat thermometer inserted in thigh reads 185F 85C. Transfer chicken to platter; tent with foil and let stand for 10 minutes before carving. Meanwhile, skim fat from pan juices. Sprinkle flour over juices; cook over medium-high heat, stirring for 1 minutes. Pour in remaining chicken stock; cook, stirring until thickened. Pour into warmed gravy boat and serve with chicken.