Trim large outer pieces of fat from the chuck and cut the beef into 3/4-inch cubes. Pat dry with paper towels. Dice the onion, mince the garlic and slice the carrots and celery 1/2 inch thick on a clean board. Keep raw beef and its utensils separate from the vegetables; wash hands and surfaces after handling raw meat.

Heat 1 tablespoon oil in a 5- to 6-quart Dutch oven over medium-high heat. Brown half the beef in a single layer for about 5–6 minutes, turning to color two sides; transfer to a clean plate. Repeat with the remaining tablespoon oil and beef. Do not crowd the pot or try to cook the centers through at this stage.

Reduce heat to medium. Add the onion and cook about 5 minutes, stirring. Add the garlic and cook 30 seconds. Pour in 1 cup of the measured broth and scrape up browned bits with a wooden spoon. Return the beef and its juices, then add the remaining broth, thyme and pepper.

Bring just to a boil, reduce to low and cover with the lid slightly ajar. Simmer gently for 90–120 minutes, stirring occasionally, until a fork enters the beef easily with only slight resistance. Add a little water if evaporation exposes the meat or overly concentrates the broth. Tougher pieces may need longer; do not add the vegetables while the beef is still firm.

Stir in the carrots and celery. Simmer gently for another 20–25 minutes, until the vegetables are tender and the beef yields readily to a fork. Taste and add up to the measured 1/2 teaspoon salt according to your broth.

During the last 10 minutes of simmering, bring a separate saucepan of water to a boil. Cook the egg noodles according to package directions, usually 7–8 minutes, until just tender. Drain in a colander. Keep them separate from the soup pot, especially if saving leftovers.

Divide the cooked noodles among six bowls. Ladle over equal shares of the beef, vegetables and broth; sprinkle with parsley. Refrigerate unused soup and noodles separately in shallow containers promptly.