Season Roast on all sides with kosher salt (if you have Red Boat salt even better!). Be generous and gently rub it in. Crack some pepper over top, too. Do this an hour or so before you're ready to cook. Let the roast sit at room temp for an hour before searing.
Pat the roast dry. Heat a thin layer of avocado oil in a dutch oven until shimmering. Brown roast well on all sides. Take your time doing this so that you get really nice, beautiful color on all surfaces- it will pay off with flavor!
While roast is browning split a full head of garlic crosswise (so all of the cloves are exposed) . Place in a piece of cheesecloth along with 2 bay leaves, a few sprigs of fresh thyme and a sprig of rosemary. Gather up edges of cheesecloth and tie with butchers twine.
Once roast is browned, remove it from dutch oven and place it on a plate. If there's a lot of fat in the pan drain off all but a Tablespoon or two. Add onions to pan and cook over medium heat until soft, about 5 minutes. Stir in tomato paste (and anchovy paste, if using) and stir until fragrant. Add 3 cups beef broth and stir well.
Nestle roast into juices in pan. The liquid should come up to about 1-2 inches below the roast's surface. If it doesn't, add more broth. Spoon some of the liquid over top of the roast. Add garlic/herb bundle to the pot and push it down into the juices. Grind some cracked pepper over the top. Cover tightly and place in a 300°f oven. Total cook time for the roast will be 3 to 4 hours.
Check roast at 3 hours using a pair of tongs to see if the roast pulls apart easily. If it's done there will be no resistance and it will be meltingly tender. If there's ANY resistance, spoon some liquid over the top again, put the lid back on and cook longer, checking every 30 minutes, or until it's fall apart tender. If your roast is on the large side it could take longer, trust the way it feels when you try to pull it apart!
When it's ready, remove the roast to a large serving platter and cover with foil to keep warm.
Remove the herbs/garlic to a dish. Keep the garlic and toss the herbs. Let the garlic cool just until you can handle it. Squeeze the soft garlic cloves out of the papery skins and into to the pot. Use an immersion blender to smooth everything out (see notes if you don't have an immersion blender). Taste the sauce and add salt and pepper to taste.
Pull roast apart into serving size pieces and drizzle some of the juices over. Serve the remaining juices along side. Alternatively you can just put the roast back into the dutch oven, pull it into chunks turning in the juices and serve right from the pot. Either works!