01 - Preheat oven to 325°F.
02 - Pat the beef roast dry and season with salt and pepper on all sides.
03 - Heat vegetable oil in a large Dutch oven over medium-high heat. Sear the roast on all sides until well browned, about 4-5 minutes per side. Remove and set aside.
04 - Add onions and garlic to the same pot. Sauté for 2-3 minutes until fragrant.
05 - Add carrots, celery, and baby potatoes to the pot. Stir to coat with the aromatics.
06 - Return the roast to the pot, nestling it among the vegetables.
07 - Pour in beef broth, water, and Worcestershire sauce. Sprinkle in thyme, rosemary, and add bay leaves. Bring to a simmer.
08 - Cover with a tight-fitting lid and transfer to the oven. Braise for 2.5 to 3 hours until fork-tender.
09 - Boil russet potatoes in salted water until fork-tender, about 15-20 minutes. Drain, mash with butter and milk, and season with salt and pepper.
10 - Steam or boil green beans until just tender, about 5 minutes. Drain, toss with butter and garlic powder.
11 - Remove beef and vegetables to a platter. Discard bay leaves.
12 - Skim excess fat from pot juices. Mix cornstarch with cold water to make a slurry. Bring pot juices to a simmer, whisk in slurry, and cook until thickened, 2-3 minutes. Adjust seasoning.
13 - Slice or shred pot roast. Serve with vegetables, mashed potatoes, green beans, and gravy.