Season the flour with mustard, cayenne, salt, and pepper. Toss the oxtail pieces in the seasoned flour, then sauté them in a large pan in half of the butter with the carrots, onions, and bouquet garni until they are a good brown color. Moisten with the brandy and set it alight. When the flames die, add the garlic and mix well. Pour in the wine, mix again, and bring to a boil.