Sauté Bacon: In a Dutch oven over medium heat, render the bacon fat until the pieces turn crispy and golden, about 5-7 minutes. Remove the bacon and set it aside, leaving the fat in the pot.

Brown Beef: Pat the beef cubes dry with paper towels and season them with salt and pepper. In batches, brown the beef in the reserved bacon fat for approximately 12-15 minutes until each piece is crusty and brown on all sides.

Cook Aromatics: Remove the browned beef and set it aside. In the same pot, add the chopped onions and carrots, cooking them for about 8 minutes until softened. Stir in the garlic and tomato paste, allowing them to sauté for 1 minute.

Create Braising Liquid: Sprinkle the flour over the sautéed vegetables, stirring to coat them briefly. Deglaze the pot with red wine, scraping the browned bits off the bottom. Add the beef broth, thyme, and bay leaves, then return the beef to the pot.

Braise: Bring the mixture to a gentle simmer, then cover the pot. Transfer it to a preheated oven set at 325°F (160°C) for approximately 2 to 2.5 hours.

Finish: During the last hour of cooking, sauté the pearl onions and mushrooms until lightly browned and tender. Fold these into the braised beef when you remove the pot from the oven.