1 rump roast (3 to 5 lbs)
1 pkg dry onion soup mix
1/3 cup water
1 can jellied cranberry sauce
2 tbsp softened butter
2 tbsp all-purpose flour
Sprinkle the onion soup mix in the bottom of crockpot or slow cooker; pour the water over the soup mix. Stir the mixture to blend. Place the roast in the cooker over the soup mixture. Spoon the cranberry sauce around and over the roast.
Place the cover on the cooker and cook on low for 10 to 12 hours. Remove the roast from the cooker to rest.
Blend the softened butter and flour together. Whisk the mixture into the juices in the cooker. Replace lid and cook on high heat for 10 minutes.
Slice the roast and serve sauce over the beef.