Brown the meat in lard a casserole dish.
Take it out and slowly add the flour to the fat left behind in the dish. Add a cup and a half of water as well as the bouquet garni, celery, and seasoning.

Put the roast into the oven and cook for 20 minutes for every 500 g of meat. While this is cooking, peel the Brussels sprouts and put them into salted boiling water. They should cook for half and hour.
Once the sprouts are being boiled, grill the chestnuts in a fry pan with holes over a hot flame.
You will need to shake the pan constantly for about 5 minutes.

About half an hour before the meat is done, cook the peeled chestnuts in a casserole dish. When it is time to serve the dish, add the Brussels sprouts, sauté for several minutes, slice the meat, and garnish the dish with Brussels sprouts on one side and chestnuts on the other.