Slow-Cooker Old-Fashioned Beef Stew

1 tablespoon vegetable oil 1 1/2 lb beef stew meat, cut into bite-size pieces if needed 4 medium carrots, cut into 1/2-inch slices (2 cups) 3 medium red potatoes, peeled, cut into 1/2-inch cubes (3 cups) 1 large onion, cut into 1-inch pieces (1 1/2 cups) 1 medium stalk celery, cut into 1-inch pieces (1 cup) 3 cups vegetable juice 3 tablespoons quick-cooking tapioca 1 tablespoon beef bouillon granules 2 teaspoons Worcestershire sauce 1/4 teaspoon pepper