Place roast in the slow cooker with pickle slices, pickle juice ranch seasoning, beef broth, and onion. Add potatoes if you like
Slow cook on high for 10 hours or on low for 5-6 hours
Add sour cream to the top of the roast about 1 hour before serving.
Place roast in the Instant Pot with pickle slices, pickle juice, ranch seasoning, beef broth, and onion. Add steamer basket on top of the roast with potatoes if you like.
Cook on high pressure for 30 minutes. And use quick release if you cooked the roast with potatoes. Cook for 45 minutes if you cooked without potatoes.
Add sour cream to the roast after, and saute the roast in the sauce.