In a medium saucepan over medium-low heat, melt 5 tablespoons of butter. Add the shallots and cook stirring occasionally for about 5-7 minutes or until soft and translucent. Add the wine, beef broth, thyme sprigs, salt, pepper, and sugar, and bring to a boil. Cook over medium heat for about 35-45 minutes, or until the liquid is reduced by about half.

While the wine mixture is reducing, place the remaining 3 tablespoons of softened butter in a small bowl and add the flour. Mix the butter and flour until a smooth paste is formed.

Using a thin sharp knife (like a utility or paring knife), trim the silver skin (the silver thin membrane of chewy connective tissue on the beef surface). Then, tie the tenderloin. If one end is more tapered than the other, bend it under the roast and secure it when tying so the roast is an even thickness throughout.

Pat dry the beef tenderloin and season it generously with salt and ground black pepper. Let the beef stand at room temperature for 1 hour.

Set an oven rack in the middle position and preheat the oven to 400 degrees Fahrenheit.

Meanwhile, carefully discard some of the fat from the skillet. Set the pan on the stovetop and add the 1/4 cup of beef broth. Bring to a boil and using a wooden spoon scrape the brown bits from the bottom of the pan.

Remove the skillet from the heat and add the broth from the skillet to the red wine sauce. Mix to combine and then bring the sauce to a simmer over low heat for about 2-3 minutes. Remove from the heat.

Slice the beef tenderloin and serve with the wine sauce.