1. For the beef: Preheat the oven to 450 degrees F. Set a rack in a roasting pan. Heat a large skillet over medium-high heat until hot. While the pan heats, pat the meat dry and season it generously with salt. Roll the tenderloin in peppercorn mixture to coat, making sure to press the ends in mixture as well. Add vegetable oil to the skillet and heat just until smoking. Brown the meat all over, turning as each side reaches a deep mahogany, about 8 minutes in all. While the meat browns, toss the unpeeled shallots with the olive oil and scatter them in the roasting pan. Transfer the meat to the rack (save the skillet) and roast until an instant-read thermometer inserted in the center registers 125 degrees F, about 30 minutes. Let the meat rest for 10 minutes before carving.

2. For the sauce: Wipe any burned bits from the skillet. Add 1 tablespoon of the butter and the sliced shallots to the skillet and cook over high heat until tender, about 2 minutes. Add wine and vegetable broth and scrape the brown bits from the bottom of the skillet with a wooden spoon. Bring to a brisk boil and cook until reduced by about half. Meanwhile, in a small bowl make a paste with remaining 4 tablespoons butter and the flour. Whisk the butter mixture into the reduced wine mixture a little bit at a time. Return to a full boil and cook until thickened, about 2 minutes. Season with salt and black pepper to taste.

3. Slice the beef and arrange it on a platter with the roasted shallots. Drizzle some sauce over the meat and serve, passing the remaining sauce.