6lbs boneless chuck roast (1 large or 2 medium pieces)
2 tablespoons canola oil
2 tablespoons unsalted butter
2 onions, minced (about 3 cups_
1 tablespoon chopped garlic
2 tablespoons tomato paste
1 tablespoon all-purpose flour
3 leeks, washed well and cut crosswise into large coins
1 1/2 lbs carrots, peeled and cut into large pieces
2 lbs baby dutch gold potatoes, large ones halved, smaller ones left whole
3 cups beef broth
4 sprigs fresh thyme plus 1 teaspoon chopped fresh thyme
2 sprigs rosemary plus 1 teaspoon chopped fresh rosemary
coarse kosher salt, to taste
freshly ground black pepper, to taste
1 tablespoon dijon mustard plus more for serving
Preheat oven to 325˚F. Trim beef of any excess fat or sinew and season generously on both sides with salt and pepper.
Pre-heat empty 7 ¼-qt Dutch Oven over medium-high heat for 2 minutes. Add oil, then add beef and sear until dark brown on both sides, about 5 minutes per side. Transfer to a large plate and reduce heat to medium low.
Add butter and onions and cook until soft, stirring to scrape up the brown bits on the bottom of the pan, about 8-10 minutes. Stir in garlic and tomato paste and cook 2-3 minutes, until tomato paste starts to caramelize.
Stir in flour and cook for 1 minute longer, then stir in beef broth. Tie together whole sprigs of thyme and rosemary with butcher’s twine and add to the pot. Bring to a simmer over medium heat.
Add prepared vegetables and seared beef to the pot. Return to a simmer, then cover and transfer Dutch Oven to the preheated oven. Cook covered until vegetables are tender and meat just begins to shred when prodded with a fork, about 3 ½ hours. Remove the lid and return pot to the oven uncovered for an additional 30 minutes.
Remove pot from oven and transfer meat and vegetables to a platter. Discard the herb bundle.
Place the Dutch Oven on the stovetop over medium-high heat and bring the sauce to a boil. Add chopped thyme and rosemary and simmer until sauce reduces and thickens slightly, about 10-15 minutes. Stir in Dijon mustard and season with salt and pepper as needed. Spoon sauce over the platter of meat and vegetables and serve with additional sauce and mustard on the side.