Pat the beef cubes thoroughly dry with paper towels. This is crucial for achieving a good sear and preventing the beef from steaming rather than browning.

Season the beef generously with salt and freshly ground black pepper on all sides. Ensure even coating.

Heat 15ml (1 tbsp) of olive oil in a large, heavy-bottomed Dutch oven or oven-safe pot over medium-high heat until shimmering. Add the beef in batches, ensuring not to overcrowd the pot. Sear for 3-4 minutes per side until deeply browned. Remove the seared beef to a plate and set aside. Repeat with remaining beef.

Add the lardons (bacon pieces) to the same pot and cook over medium heat, stirring occasionally, until crisp and rendered, about 6-8 minutes. Remove the crispy bacon with a slotted spoon and set aside with the beef. Leave the rendered bacon fat in the pot.

Add the chopped yellow onions and carrot chunks to the pot with the bacon fat. Cook over medium heat, stirring occasionally, until the onions are softened and translucent, about 8-10 minutes. Add the minced garlic and cook for another minute until fragrant.

Sprinkle the all-purpose flour over the vegetables and stir well to coat. Cook for 1-2 minutes, stirring constantly, to cook out the raw flour taste. This will help thicken the stew.

Add the tomato paste to the pot and stir it into the mixture. Cook for 1 minute, stirring, to deepen its flavor.

Pour in the red wine and scrape the bottom of the pot with a wooden spoon to deglaze, loosening any browned bits (fond) stuck to the bottom. Bring to a simmer and cook for 5 minutes, allowing some of the alcohol to evaporate.

Return the seared beef and crispy bacon to the pot. Add the beef broth, thyme sprigs, and bay leaf. The liquid should almost cover the meat and vegetables; add more beef broth or water if needed. Bring the mixture to a gentle simmer.

Preheat your oven to 160°C (320°F). Once the stew is simmering, cover the Dutch oven tightly with its lid and transfer it to the preheated oven.

Braise in the oven for 2.5 to 3 hours, or until the beef is fork-tender. Check periodically to ensure it's simmering gently and not boiling.

While the beef is braising, prepare the garnish. Melt the butter in a large skillet over medium-high heat. Add the quartered mushrooms and cook, stirring occasionally, until golden brown and tender, about 5-7 minutes. Remove mushrooms from the skillet and set aside.

Add the peeled pearl onions to the same skillet (add a little more butter if needed). Cook over medium heat, stirring occasionally, until they are tender and lightly caramelized, about 10-15 minutes. Set aside with the mushrooms.

Once the beef is tender, carefully remove the Dutch oven from the oven. Remove and discard the thyme sprigs and bay leaf. Skim off any excess fat from the surface using a spoon or ladle.

Stir in the sautéed mushrooms and pearl onions into the stew. Taste and adjust seasoning with salt and pepper if necessary. If the sauce is too thin, you can simmer it uncovered on the stovetop over medium-low heat for 10-15 minutes to reduce and thicken it.

Serve the Beef Bourguignon hot, garnished with fresh chopped parsley. It is traditionally served with mashed potatoes, crusty bread, or egg noodles.