Season the chuck roast generously on all sides with salt and pepper.
Heat vegetable oil in a large Dutch oven or heavy pot over medium-high heat and brown the roast on all sides, about 4-5 minutes per side.
Remove the roast and set aside, then add the minced garlic and onion to the pot, cooking for 2 minutes until fragrant.
Return the roast to the pot and add beef broth, diced tomatoes, thyme, and rosemary.
Bring to a boil, then reduce heat to low, cover, and simmer for 2 hours.
Add the carrots and potatoes to the pot, nestling them around the roast, then cover and continue cooking for 1 more hour until meat is fork-tender and vegetables are cooked through.
Remove the roast and vegetables to a serving platter, then whisk flour into the cooking liquid to thicken into gravy.
Slice the roast and serve with vegetables and gravy spooned over the top.