In a large skillet, cook onion and garlic in hot oil over medium heat about 4 minutes or until tender. Stir in shredded beef, undrained tomatoes, corn, beans, and chili powder. Bring to boiling; reduce heat. Simmer, uncovered, about 5 minutes or until heated through and desired consistency.

Meanwhile, in a small bowl, stir together cucumber, jicama, and cilantro. Divide beef and vegetables among tortillas. Top with cucumber mixture and sour cream and/or guacamole. Makes 6 servings.

To warm tortillas, wrap in foil and place in a 350 degree F oven for 10 minutes.

Trim fat from a 3 to 3-1/2 pound boneless beef chuck pot roast. If necessary, cut beef to fit a 4- to 5-quart slow cooker. Place 2 large onions, cut into thin wedges and 2 cloves garlic, minced in the cooker. Top with beef. In a medium bowl, combine 1, 14-ounce can beef broth, 1 tablespoon Worcestershire sauce, 2 teaspoons dry mustard, 1 teaspoon dried thyme, crushed; 1/2 teaspoon salt, and 1/4 teaspoon cayenne pepper. Pour over beef in cooker. Cover and cook on low-heat setting for 11 to 12 hours or on high-heat setting for 5-1/2 to 6 hours. Remove beef and onion from cooker, reserving juices. Using two forks, shred beef, discarding any fat. Skim fat from juices. Add onion to beef; add enough juices to beef to moisten. Place 2-cup portions of beef in airtight containers and refrigerate for up to 3 days or freeze for up to 3 months. Makes 6 cups.