2 Tablespoons olive oil
1 onion, chopped—optional! (I skipped it)
2 pounds beef cubes or ground beef (I used beef sirloin cubes, which were great)
6 to 8 cups water
2 Tablespoons cider vinegar
2 Tablespoons Worcestershire sauce
2 teaspoons salt
2 teaspoons ground black pepper
1 Tablespoon cornstarch