Pat the roast dry, season with salt and pepper, and brown it in the oil in a hot skillet for 4 minutes per side.
Mix the parsley, dill, garlic powder, onion powder, chives and paprika. Put the roast in a 6-quart slow cooker and sprinkle the seasoning over it.
Pour the broth, Worcestershire and pepperoncini brine around the meat. Add the whole peppers and dot the roast with butter.
Cover and cook on low for 8 hours, until the beef shreds easily. Transfer the beef to a platter and skim excess fat from the liquid.
Mix cornstarch and cold water, stir it into the liquid, and cook on high for 10 to 15 minutes. Pull the beef into large pieces and spoon the pepperoncini gravy over it.