Pull the roast out of the fridge, sprinkle all sides with salt & pepper, and set aside for about 10 minutes to warm up. Meanwhile, make the homemade onion soup mix (this should only take about 1-2 minutes using spices you have on hand). Use this time to also prep the veggies by peeling the onions then slicing them into wedges, chopping the celery, then peeling and chopping the carrots and parsnips. (Make sure to save all the veggies scraps to use for homemade stock.)

Sprinkle one tablespoon of the onion soup mix over the roast (get all sides), pressing the seasonings down into the meat, if needed. Place a skillet or large pot over medium heat, then add 1 tablespoon of cooking oil. When that's warm (should take 1-2 minutes), lay the roast in the pan (it should sizzle when you add it). Sear all sides of the roast using tongs to flip the meat (I let the big sides cook for 1 ½ minutes and the other sides for 30-45 seconds), then transfer the pot roast to the slow cooker.

Reduce heat to medium-low, measure in another tablespoon of cooking oil, and add in the onions. Season to taste with salt & pepper. Cook, stirring occasionally, for 2 minutes. Remove the onions from the skillet and place them around the pot roast in the slow cooker. Repeat the process with the carrots, parsnip & celery (all cooked together), then place those in the slow cooker, as well.

Measure the broth into a cup or bowl, then pour about ¼ cup of it into the skillet. Use a wooden spoon to scrape up the fond (flavorful beefy bits) from the bottom of the skillet, then add the remaining 2 tablespoons of onion soup mix into the skillet and slowly pour in the rest of the broth while stirring. Let the broth warm-up for a few minutes (no need to bring it to a simmer) then pour it into the slow cooker over the veggies.

Cover the slow cooker with its lid and cook on HIGH for 4-5 hours OR on LOW for 8-10 hours, or until the meat is fall-apart-tender and the veggies are fully cooked.

Serve the pot roast shredded or in big chunks with extra drippings/juices poured over it. Alternately, you can use the drippings/juices to make a quick homemade gravy using a roux or cornstarch (see notes below) to pour over it.