• Preheat oven to 300°F.
• Add 1 cup of the beef broth, the chuck roast and the celery flakes into the Dutch oven. Season the roast with kosher salt and pepper. Arrange onion wedges on top of and around the roast.
• Cover the Dutch oven and bake, turning once halfway through cooking and seasoning with salt and pepper, for 2 1/2 to 3 hours or until your roast has an internal temperature of 200°F, or is fork-tender. Add more broth, if needed, during cooking.
• In a large heavy bottom skillet over medium-high heat, add the oil and heat until shimmering. Transfer the chuck roast to the skillet and sear, turning once, about 4 minutes per side or until the roast is nicely browned, adding more oil as necessary. Transfer the roast to a cutting board. Cover the roast with foil and let stand for 5 to 10 minutes.
• Carve the roast into thick slices or chunks and transfer to a serving platter. Using a slotted spoon, remove the onions and arrange around the roast, if desired.
• Skim fat from the juices in the Dutch oven. Add remaining beef broth and heat over medium heat until warm. Ladle mixture into a gravy boat and serve. Or, use the mixture to make the beef gravy below.

Beef Roast Gravy (optional)

• Skim fat from the juices in the Dutch oven. Transfer juices to the skillet used for browning the roast. Add remaining beef broth to the skillet until you have about 2 cups of liquids. Over medium heat, cook, scraping up any browned bits from the bottom of the pan, until simmering.
• In a small bowl, whisk together the cold water and cornstarch. Slowly whisk slurry into the juices and cook, stirring, 3 to 5 minutes or until gravy is thickened to your liking. Season to taste with salt and pepper.
• Strain gravy into a gravy boat. Serve with the chuck roast.