In a large roasting bag which has been dusted with flour on the inside place 1 carrot, 1 celery stick and 1 small red onion, all finely chopped. Dot with slices of lemon and a few whole garlic cloves. Season a whole chicken with salt and pepper, fill its cavity with a quartered lemon, some whole thyme sprigs and a few garlic cloves, and place into the bag. Drizzle 2tbs melted goose fat (or olive oil) over the chicken and sprinkle with fresh thyme leaves. 

Add 1 small glass of water to the bottom of the bag before securing the opening with a tie. Cut a a couple of slit in the top of the bag and then place in a hot oven (200c) for about an hour and quarter. To check if the chicken is done, pierce the inside of the thigh with a knife. If the juices run clear take out of the oven.

Carefully open the bag and extract the chicken. Cover and let rest for 10 minutes before serve alongside the juices and vegetables (carefully poured out of the bag into a serving dish . 

Serve the chicken with you favourite sides.