01 - Preheat oven to 325°F.
02 - Pat the beef roast dry with paper towels and season generously 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 deeply browned, about 4-5 minutes per side. Remove roast and set aside.
04 - Add onions and garlic to the same pot. Sauté for 2-3 minutes until fragrant and onions begin to soften.
05 - Add carrots, celery, and baby potatoes to the pot. Stir well to coat with the aromatic base.
06 - Return the seared roast to the Dutch oven, nestling it among the vegetables.
07 - Pour in beef broth, water, and Worcestershire sauce. Sprinkle with thyme, rosemary, and add bay leaves. Bring to a gentle simmer.
08 - Cover with a tight-fitting lid and transfer to the oven. Braise for 2.5 to 3 hours until beef is fork-tender.
09 - Boil russet potatoes in salted water until fork-tender, about 15-20 minutes. Drain well and mash with butter and milk. Season with salt and pepper to taste.
10 - Steam or boil green beans until just tender, about 5 minutes. Drain thoroughly and toss with butter and garlic powder.
11 - Transfer the beef and vegetables to a serving platter. Discard bay leaves.
12 - Skim excess fat from the pot juices. Whisk cornstarch with cold water to make a smooth slurry. Bring pot juices to a simmer on the stovetop, whisk in the slurry, and cook until thickened, 2-3 minutes. Adjust seasoning as needed.
13 - Slice or shred the pot roast. Serve alongside vegetables, mashed potatoes, green beans, and gravy.