3. Discard half the fat and return the pan to the stove over medium heat. Add the onion, fennel, carrot, thyme sprigs, bay leaf, and a pinch of pepper. Cook for about 10 minutes, stirring often with a wooden spoon to scrape up all the crusty bits. When the vegetables are nicely browned and caramelized, add the balsamic vinegar and banyuls. Turn the heat up to high, bring the liquid to a boil, and cook for 6—8 minutes, until it has reduced by half. Add 3 cups stock and bring to a boil. Turn the heat down to low and simmer for 5 minutes.