Heat the oil in a medium saucepan and cook the carrots, onions, shallots, and bouquet garni until softened, about 10 minutes, stirring occasionally. Pour in the vinegar and wine and bring to a boil. Reduce heat and simmer until reduced by half. In a large saucepan melt 2 tablespoons of the butter. Whisk in 2 tablespoons of the flour and cook, stirring constantly, for 2 minutes. Stir in 2 1/2 cups of the beef stock and the contents of the first saucepan and bring to a boil. Reduce heat and simmer for 1 hour, skimming from time to time. After 45 minutes, add the crushed peppercorns and continue cooking for 15 minutes. Strain the sauce through a fine mesh strainer. Return the sauce to the saucepan and simmer for 45-50 minutes longer, skimming occasionally. From time to time add some of the remaining beefstock. Remove the pan from the heat and whisk in the remaining butter. Season with salt and pepper. Do not return the sauce to the heat.
