Grease a 6 quart crockpot with cooking spray. Set aside.
Whisk together spices in a small bowl: paprika, onion powder, garlic powder, parsley flakes, salt, pepper, and celery seed. Set aside.
Place veggies into crockpot and sprinkle with half the spices. Set aside.
Rub the roast in the remaining spices.
Melt butter in a large non-stick pan over medium high heat.
Once melted, add in roast and brown for 4-5 minutes on both sides. The roast will not be cooked through, you’re just looking for a nice sear on both sides.
Place roast on top of veggies.
Pour over broth, red wine, and worcestershire.
Cover and cook on low for 10 hours or HIGH for 5 hours.
In the last hour of cooking, whisk together vinegar and cornstarch in a small bowl.
Stir into crockpot, re-cover, then cook for an additional hour.
Shred the meat directly in the crockpot and serve!