Place roast in a slow cooker and cover with salsa (or any Mexican sauce), tomato sauce, and taco seasoning. Cook on low for 8 hours. Remove beef from slow cooker and keep warm.
2.
In a small bowl, whisk together the cornstarch and cold water; add in a thin stream to the slow cooker, and stir to thicken. Repeat if you need to to get the gravy consistency you want.
