Mix together olive oil, lemon zest, garlic and herbs. Season and brush over chicken.
Place the onion and halved lemon inside the chicken cavity and place chicken on rack in roasting tin.
Cook in centre of oven at 190°C, 170°C fan oven, Gas Mark 5 allowing 20 minutes per 450g (1lb) plus an extra 20 minutes. Baste occasionally during cooking.
Meanwhile, make the gravy by first pouring off the fat from the roasting juices. Add the Knorr Gravy Pot with 280ml vegetable water to the roasting tin and slowly bring to the boil, stirring continuously. Boil for 1 minute.
Serve with roast potatoes, your choice of seasonal vegetables, bread sauce and Knorr gravy.
