Ensure your oven rack is positioned in the center of your oven. Preheat your oven to 300 degrees F.
Pat the roast dry with paper towels. Season with salt and pepper.
Heat olive oil in a large oven-safe Dutch oven (with at least a 5.5-quart capacity) over medium high heat. Add the roast and sear on all sides until deep golden brown (about 3 minutes each side). Add more olive oil if necessary while searing. Carefully remove the roast (using tongs) and transfer to a large plate.
Pour in the red wine and stir (using a wooden spoon), scraping up any browned bits from the bottom of the pot.
Add garlic and cook until fragrant (about 30 seconds), stirring constantly. Pour in beef broth and stir to combine.
Remove the pot from the heat and return the roast (along with any juices) to the Dutch oven.
Arrange the onion wedges around the outside of the roast (as evenly as possible).
Evenly sprinkle Italian seasoning over the roast and onions. Add the bay leaf.
Cover and bake for 2 hours.
After 2 hours, carefully remove the Dutch oven (using oven mitts!). Arrange the carrots, celery, and potatoes around the roast. Cover and bake for an additional 1 ½ to 1 ¾ hours, or until the roast and veggies are fork-tender. Remove and discard bay leaf.
Make the gravy: Carefully remove the roast with tongs and transfer to a large platter. Remove the vegetables using a slotted spoon and transfer to the platter with the roast. Whisk the cornstarch and water in a small bowl or large measuring cup until smooth and combined. Bring the broth to a simmer in the Dutch oven on the stovetop. Slowly pour in the cornstarch slurry while whisking to combine. Simmer for 3 minutes or until thickened.