Meat adds a hearty flavor to this soup. Add some barley and let it be a whole dinner in one!
Heat the oil in a large pot, and add the onion, fennel, and garlic. Sauté for about five minutes, until soft. Add the flanken and cook for 8–10 more minutes. If the onions are burning, add 1/4 cup of water. Add the chicken or beef stock and the potato, and cook for about 1/2 an hour.
Add 3 and 1/2 cups frozen peas, salt, pepper, and basil, and cook for about 20 minutes. Remove the meat and set aside. Blend the soup with an immersion blender and add the remaining 1/2 cup of peas, meat, and barley, if desired. Heat and serve.