Place 2 pounds beef chuck roast, cut into 1-inch pieces, in the bottom of a 6-quart crock pot.
Add ½ onion diced, 3 large carrots peeled and cut into large pieces, 3 large red potatoes quartered, 1 tablespoon minced garlic, 2 cans diced tomatoes with green chiles (10 ounces each), 1 bay leaf, 2 tablespoons taco seasoning, and 2 cups beef broth to the crock pot.
Cover and cook on low for 6-8 hours or on high for 3-4 hours.
In a small bowl, mix 2 tablespoons cornstarch with ¼ cup cold water until smooth. Stir this mixture into the crock pot during the last hour of cooking on low or the last 30 minutes on high to thicken the stew.