Corned Beef Soup

Bahan-bahan (6 porsi)

• 1 tablespoon olive oil
• 1 small onion (chopped small, about ½ cup )
• 4 -5 celery ribs (sliced thin, about 1½ cups )
• 2 large potatoes (peeled and chopped into ½" pieces, about 4 cups )
• 6 cups beef broth (or 6 cups water, plus 2 tablespoons beef base)
• 1 tablespoon Worcestershire sauce
• ½ teaspoon freshly ground black pepper (plus more to taste)
• 1 small head green cabbage (quartered and sliced thin, about 6 cups )
• 2 cups cooked corned beef (roughly chopped into ½" pieces)
• kosher salt (only as needed )