Combine all ingredients, except water, in a zippered freezer bag, squeeze out all of the air, zip and freeze.
Take the bag out of the freezer the night before you want to cook and serve. In the morning pour the contents into the slow cooker, making sure the potatoes and carrots are on the bottom and place tenderloin on top. Pour ½ cup water over the loin.
Cook on low for 8-10 hours until the potatoes and carrots are cooked through. Keep an eye on the potatoes to ensure that they stay submerged in liquid and do not brown or burn.