Take the roast and brown it on all sides, seasoning with salt and pepper and chopped onions. When it is browned, put in a crockpot with a 1/3 cup of water. Sprinkle ½ of the packet of ranch dressing directly onto the roast. Sprinkle half of the packet of Au Jus directly onto the roast and put the lid on. Let cook on low for four to six hours, and enjoy your juicy, delicious roast!