Heat canola oil over med-high heat. Season roast with salt and sear in hot oil until golden brown.
Place roast in crock pot and sprinkle with dressing mix, pepperoncinis, pepperoncini juice, and dot with butter.
Cook in crock pot on LOW for 6-8 hours or HIGH for 3 ½ -4 or until the roast is fork-tender. Remove meat from pot and drain off cooking juices into a sauce pan, skimming the top for excess fat. Add 2 cups of beef broth to the juices and bring to a boil.
Mix 1 tbsp of corn starch with ¼ C of COLD water and slowly pour into the boiling broth mixture. Stir continuously until thickened and remove from heat. Stir in ½ cup of sour cream into the thickened broth and serve over the cooked meat.