Preheat your oven to 350°F (175°C).

In a Dutch oven over medium-high heat, add diced bacon and sauté for about 5-7 minutes until crispy. Remove bacon, leaving the fat.

Pat dry beef cubes and season with salt and pepper. Sear each cube in bacon fat for 3-4 minutes per side until browned. Remove and set aside.

Add diced onions and chopped carrots to the pot, sauté for 2-3 minutes until softened. Stir in minced garlic and cook for an additional minute.

Add tomato paste, stirring to caramelize for 1-2 minutes. Sprinkle flour over the mixture and cook for another 2-3 minutes until lightly golden, forming a roux.

Pour in red wine slowly, scraping up the fond. Add beef broth and bouillon, mixing thoroughly.

Return seared beef and bacon to pot. Toss in thyme and bay leaves and bring to a simmer.

Cover with lid and transfer to oven, braising for 2.5 hours.

In a skillet, heat butter and add mushrooms and pearl onions, sautéing for 5-7 minutes until browned. Set aside.

After braising, stir in sautéed mushrooms and pearl onions. Cover and return to the oven for an additional 45-60 minutes.

Remove from oven, let rest for 30 minutes before serving. Adjust seasoning as needed.