Set your roast out to come to room temperature while you prep all of your vegetables.

Preheat the oven to 350 degrees.

Using paper towels, pat the roast dry all the way around, and then season it liberally with salt and pepper.

Put a large Dutch oven (or braising pot—just make sure what you use is deep, has a lid and is oven-safe) on the stovetop and heat the oil on medium-high heat.

Add the roast, and sear it on all sides, cooking each side for about three or four minutes. Transfer the meat to a plate, and add the onion and leeks, along with just a bit more salt. Saute, stirring regularly, until they are soft.

Add the garlic to the pot and saute for one or two minutes until it just starts to brown and is fragrant.

Stir in the tomato paste, making sure to incorporate everything in the pot well.

Pour in the wine, and using a wooden spoon or spatula, scape the bottom of the pot to get all the stuck on bits up. Let this cook for two or three minutes, and then add the beef stock, Worcestershire sauce, mustard, bay leaves, thyme (I tied mine together in a bundle with cooking twine so it will be easy to remove later), and carrots.

Add the roast back to the pot, pushing it down into the ingredients so that it’s mostly submerged.

Cover with a lid and put the pot in the oven. Cook until the meat is tender enough to shred with a fork, which will take about three hours.

Remove the pot from the oven and use tongs to carefully put the roast on a cutting board. Let it rest for five to 10 minutes before shredding it with two forks.

Meanwhile, remove the thyme and bay leaves from the pot. Taste the sauce and add salt and pepper, if needed. Add the shredded beef back to the pot, and stir.

Serve the beef and veggies over mashed potatoes, along with some of the amazing sauce you created.