In a bowl, combine broth, 1 tablespoon cumin, garlic and tomato sauce.
Pour over the top of the roast.
Covering the slow-cooker, cook on LOW for 6 to 8 hours.
Transfer meat to a cutting board.
Using two forks, shred the beef.
Strain the juices from the slow-cooker and save the juice.
Transfer shredded meat back to the slow-cooker.
Pour some of the strained juices over the shredded beef.
Add the enchilada sauce and tomato paste.
Add salt and extra cumin, to taste, for seasoning.
Serve in taco shells with desired toppings.
Tomatillo dressing:
Blend all ingredients for the dressing in a blender or food processor, until smooth and creamy. Taste and adjust any flavors as needed. Refrigerate until ready to use.