Preheat the oven to 350 F.
Put 3 tbsp of oil into the Dutch oven with the heat on medium-high.
Cut the brisket into manageable chunks that will fit into your Dutch oven.
Season on both sides with kosher salt and pepper.
In two or three batches, brown the brisket on both sides, about 4 minutes a side.
Transfer them to a bowl after they are browned.
Chop the carrots, onions and celery into one inch chunks.
Put them into the pot and cook them, stirring frequently until they are browned, about 5 minutes.
Add the flour and tomato paste and mix. Cook for another 4 minutes until dark red.
Add the wine, brown sugar, brisket, and any juices that have accumulated. Mix.
Bring to a boil, then lower the heat to medium and simmer for about 25 minutes.
Halve the garlic lengthwise, and add it to the pot along with the herbs.
Add the stock and gently stir.
Cover and place in the oven.
Cook for 2.5 hours.
Remove the brisket from the pot, and set aside.
Remove the vegetables and herbs.
Cut the brisket into thin slices.
Put the slices back into the pot and cover.
Cook for another 20 minutes.