Slow-cooker beef tacos

Beef second courses Mexican cuisine

2 pounds boneless beef chuck roast 1 teaspoon salt 1 Tablespoon vegetable oil 1 Tablespoon chili powder 1 (6-oz.) can tomato paste 2 cups beef broth 1 small white onion 1 (8-oz.) can tomato sauce 1/2 medium-size green bell pepper 1 teaspoon ground cumin 1/2 teaspoon pepper flour toppings: shredded sour