Season the roast on both sides with 1 ½ teaspoons of salt and the black pepper. Add the olive oil to a large skillet over high heat. Once the oil is hot, add the chuck roast. Sear it on both sides, about 3 minutes per side. Transfer the roast to a plate.
Turn the heat down to medium. To the same skillet that you seared the roast in, add the broth, tomato paste, garlic, rosemary, and thyme. Bring up to a simmer, whisking to combine, and then remove from the heat.
To Cook:
Spray the inside of a 6 or 8-quart slow cooker with olive oil cooking spray. Add the potatoes to the pot and spread them out evenly. Add the carrot and spread it out. Pour the diced tomatoes (with juices) on top. Add the bay leaf. Put the roast (with any juices from the plate) on top. Add the celery and onion, tucking them onto the side of the roast (it’s fine if they’re on top of the roast too). Pour the broth mixture on top.
Cover the slow cooker. Cook on LOW for 8 to 10 hours for best results, or on HIGH for 5 to 6 hours. The meat is done when it’s tender enough to pull apart with a fork.
To Serve:
Remove the vegetables and roast from the slow cooker. Carefully strain the hot liquid through a fine mesh sieve to serve it as gravy.
Garnish with parsley.
Notes
Chuck Roast: Your roast doesn't have to be exactly 3 pounds; anywhere from 2 ½ to 3 pounds is fine. Look for a chuck roast with good marbling. This will add great flavor as the pot roast cooks, and make sure the end result is extremely tender and juicy.
To Thicken the Cooking Liquid: After you strain it, transfer it to a saucepan on the stovetop over medium heat. Dissolve 2 tablespoons of cornstarch in 3 tablespoons of cold water and whisk it into the simmering liquid. Cook until thickened, about 1 to 2 minutes, whisking constantly.
Don’t Skip the Fresh Herbs: With a meal that slow cooks all day, fresh herbs really help enhance and brighten the flavor.
A Splash of Vinegar: Other than when I make this dish during Passover, I like to add about a tablespoon of red wine vinegar to the cooking liquid before serving to wake up the flavors. Storage: Store leftovers covered in the fridge for up to 4 days.