Persian noodle soup

3 lg Onions, peeled and thinly
           -sliced
      3 T  Oil
      2 t  Salt
    1/2 t  Freshly ground black pepper
      1 t  Turmeric
     10 c  Water
    1/4 c  Dried red kidney beans,
           -washed and soaked in cold
           -water for 2 hours and
           -drained
    1/4 c  Dried navy beans
    1/4 c  Dried chickpeas
    1/2 c  Lentils
    1/2 c  Beef broth, preferably
           -homemade
    1/2 c  Coarsely chopped fresh
           -chives or scallions
    1/2 c  Chopped fresh dill
    1/2 c  Coarsely chopped fresh
           -parsley
      6 c  Spinach, washed and chopped
           -OR
      3 c  Frozen spinach, chopped
      1    Fresh beet, peeled and diced
           -in 1/2" pieces
    1/2 lb Persian noodles (reshteh)
           -OR
    1/2 lb Linguine noodles
      1 T  All-purpose flour
      1 c  Liquid whey (kashk)
           -OR
    1/4 c  Wine vinegar
 
  Brown the onions in 3 tablespoons oil in a large pot. Add 2 teaspoons
  salt, 1/4 teaspoon pepper, and 1/2 teaspoon turmeric. Pour in 10 cups
  water and add kidney beans, navy beans and chickpeas; bring to boil,
  skim the froth as it forms, reduce heat, cover and simmer for 45
  minutes over medium heat.
  
  Add lentils and beef broth. Cook 55 minutes longer.
  
  Add chopped chives or scallions, dill, parsley, spinach and beet.
  Continue cooking, stirring from time to time, for 1-1/2 hours or
  until the beans are tender. Correct seasoning and add water if the
  soup is too thick.
  
  Add noodles and flour and cook about 10 minutes, stirring
  occasionally. Stir in the liquid whey (or vinegar) and mix well.
  
  Pour the soup into a tureen and serve.