When cooked properly a roast beef from the crock pot is moist and tender. Plus, this method of cooking typically requires very little prep time and generally the meal is ready to serve right out of the pot. To make an easy crock pot roast beef you need a liquid, so the meat doesn't dry out while it is slow cooking. You will also want to add something to enhance the flavour of your meat.
Place your roast beef in the crock pot. Sprinkle half of the envelope of dry onion soup mix over the top of your roast beef.
Pour the entire can of cola over your roast beef. Sprinkle the remaining dry onion soup mix over the roast beef.
Put the lid on your crock pot and turn it on. Set it to high and cook your roast beef for four hours, or set it to low and cook your roast beef for eight hours. Longer cooking times over lower heat yield meat that is more moist and tender.
Rotate your roast beef half way through the cooking time. Remove roast beef from the crock pot when the cooking time is done. Let the roast beef rest for 10 minutes before slicing it for eating.