Preheat oven to 375 degrees Fahrenheit.

In a 9-inch diameter pie pan, toss halved and peeled shallots with olive oil to coat.

Season the shallots with salt and pepper.

Roast shallots in the preheated oven, stirring occasionally, until deep brown and very tender, approximately 30 minutes.

In a large saucepan, boil beef stock and tawny port until reduced to 3 3/4 cups, about 30 minutes.

Whisk in tomato paste into the reduced stock and port mixture.

Pat beef tenderloin steaks dry and sprinkle with dried thyme, salt, and pepper.

In a large roasting pan set over medium heat, sauté chopped bacon until golden, about 4 minutes.

Transfer the cooked bacon to paper towels to drain excess fat.

Add the beef tenderloin steaks to the roasting pan and brown on all sides over medium-high heat, about 7 minutes.

Transfer the roasting pan with the beef to the oven and roast until a meat thermometer inserted into the center registers 125 degrees Fahrenheit for medium-rare, about 45 minutes.

Transfer the roasted beef tenderloin steaks to a platter and tent with foil to rest.

Spoon fat off the top of pan drippings in the roasting pan.

Place the roasting pan over high heat.

Add the stock/port mixture to the pan and bring to a boil, scraping up any browned bits.

Transfer the sauce to a medium saucepan and bring to a simmer.

In a small bowl, mix 3 tablespoons of butter and all-purpose flour to form a paste; whisk into the simmering stock and simmer until sauce thickens, about 2 minutes.

Whisk in the remaining 3 tablespoons of butter.

Stir in the roasted shallots and reserved bacon.

Season the sauce to taste.

Cut the beef tenderloin into 1/2-inch thick slices.

Spoon some sauce over the sliced beef.

Pass the remaining sauce separately.