lentil soup with spinach

i find this is a good way to use up extra tomato paste and spinach of which i always seem to have a bit extra after making other things during the week.

1 C lentils
1 medium onion, chopped
2 stalks celery, chopped
½ carrot, chopped
1 bay leaf
¼ tsp oregano
3 tbsp tomato paste
6 C liquid (4 broth, 2 water)
1 ½ tsp wine vinegar
½ bunch spinach, chopped

put all but spinach and vinegar in a soup pot and simmer 2 hours. puree half, add spinach and cook 30 min then add vinegar.