Prepare the vegetables and mushrooms: Clean the mushrooms and cut them into quarters. Peel and slice the carrots. Chop the celery, onion, and garlic.
Sear the mushrooms: In a large pot or Dutch oven, heat 1 tablespoon of oil over medium-high heat. Add the mushrooms and sauté until they are golden brown and their water has evaporated. Remove them from the pot and set aside.
Sweat the vegetables: In the same pot, add the second tablespoon of oil. Sauté the onion, garlic, carrots, and celery for about 5 minutes, until they start to soften.
Add the flour: Sprinkle the vegetables with the flour and stir well to coat. Cook for a minute to remove the raw flour taste.
Deglaze with red wine: Pour the red wine into the pot and stir well to loosen the cooking residues. Reduce by half.
Add the broth and aromatics: Add the vegetable broth, tomato paste, bay leaves, and thyme. Put the mushrooms back into the pot.
Preheat the oven to 200 degrees Celsius (392 degrees Fahrenheit) with convection setting for the potatoes if you decide to make them.
Simmer: Bring to a boil, then reduce heat and simmer covered for about 45 minutes to 1 hour, until the vegetables are tender. While the bourguignon simmers, start cooking the potatoes. The instructions follow below.
Finalization: Remove the bay leaves and thyme. Adjust seasoning with salt and pepper to taste. If the sauce is too liquid, you can thicken it by using cornstarch. Dissolve 1 to 2 tablespoons of cornstarch (Maïzena) in a little cold water, then stir this mixture into the sauce. Continue to heat for a few minutes until the sauce thickens to the desired consistency.
Serving: Serve your Vegetable Bourguignon hot, garnished with fresh chopped parsley. It pairs deliciously with steamed potatoes, mashed potatoes, or pasta.