Preheat the oven and position the rack in the lower third. Season the roast generously with salt and pepper, then let it rest at room temperature to ensure even cooking.
Heat oil in a large Dutch oven over medium-high heat. Once hot, sear the roast on all sides until a deep golden crust forms, then transfer it to a plate.
Reduce the heat and sauté the chopped onion until softened and lightly golden. Add garlic and cook briefly until fragrant, then stir in tomato paste and cook until slightly darkened.
Pour in the red wine and scrape the bottom of the pot to release any browned bits. Let it simmer until slightly reduced.
Add beef stock, herbs, and seasoning. Return the roast to the pot along with the carrots, bringing everything to a gentle boil.
Cover the pot and transfer it to the oven. Cook slowly until the meat becomes tender and easily pulls apart with a fork.
Remove the roast and shred it. Serve with the vegetables and spoon the rich sauce over the top. Thicken the sauce if desired using cornstarch or flour.