Preheat oven to 325ºF with the oven rack in the bottom third. Heat a dutch oven over medium high heat.
Pat the pot roast dry with a paper towel, then season all sides with kosher salt. (I don't season the meat with pepper because I find that browning it at this high heat gives the pepper a bitter taste.)
4 pounds boneless chuck roast, 2 tablespoons kosher salt
Brown the beef in the dutch oven by adding the olive oil, then searing the meat on all sides until it is golden brown, about 4-6 minutes per side.
2 tablespoons olive oil
Remove the meat from the dutch oven and transfer to a plate.
Scrape up all the brown bits from the bottom of the dutch oven by adding in 1 cup of the beef broth to the same dutch oven, then scrape up all the brown bits into the liquid. This is where you'll get a ton of flavor.
Layer the pot roast. Add half the carrots, celery, onion, garlic and herbs to the bottom of the dutch oven. Return the browned pot roast to the dutch oven on top of the herbs and veggies. Then arrange the remaining half of the onion, carrots, celery, herbs and garlic around the edge of the pot roast.
3 whole onions, 8 medium carrots, 8 ribs of celery, 1 head of garlic, 6 sprigs of fresh rosemary, 6 sprigs of fresh thyme
Add the broth and tomato paste to the dutch oven. You want enough to cover all the veggies, and 9/10th's of the pot roast. This will be anywhere from 6-8 cups. I like to the stir the tomato paste into 4 cups of the broth first, so it even distributes.
6-8 cups beef broth, 2 tablespoons tomato paste
Cover the dutch oven with its lid, and cook in the oven for 5 hours.
Remove from the oven. With a large spatula, lift the pot roast out from the dutch oven and transfer to a cutting board to rest. Careful! It's super tender and falls apart easily! With a slotted spoon, transfer the carrots and onions to a serving platter and tent with foil to keep warm. Discard the garlic and herbs.
Strain the fat from the pot roast braising liquid to use for the homemade gravy. You'll want 4 cups.