In a skillet or large pan over medium high heat (with about 2-3 tablespoons of oil), sear your roast on all sided, about 2 minutes per side or until browned.
In a slow cooker set to low, scatter chopped onions and celery along the bottom. Place the seared roast on the vegetables.
Sprinkle the onion soup mix and italian seasoning over the tops and sides of the roast. Pour all but 3 tablespoons of the broth on top of the roast. (Reserve the 3 tablespoons).
Cover and allow to cook for 3 hours on high, 4-5 hours on low (or 275° in the oven).
In a small cup, mix cornstarch with reserved broth. Pour broth mixture into the slow cooker and increase the heat to high for the last 30 minutes-1 hour of cooking, or until the meat is fork tender and the broth has thickened to a loose gravy.
Remove from the crock pot, sprinkle with parsley, and slice and serve immediately with the gravy over top.
