Cabbage Meatball Soup

Bahan-bahan (6 porsi)

• 1 tablespoon olive oil
• 1 medium yellow onion (diced)
• 2 carrots (chopped)
• 2 ribs celery (chopped)
• 1 tablespoon all-purpose flour
• 1 teaspoon dried oregano
• 6 cups beef broth (or chicken broth)
• 4 cups chopped green cabbage (about ¼ medium head)
• 1 (10 ounce) can diced tomatoes with chilies (such as Rotel, with juices)
• ¼ teaspoon salt (more to taste)
• ¼ teaspoon black pepper
• 16 to 20 ounces frozen meatballs (or cooked homemade meatballs)