There are certain classic combinations for soups which just seem to work together perfectly - leek and potato, for example. Another one is lentil and tomato. I made a lentil and tomato soup yesterday - and it was ideal for fighting off the the November chill (since I returned to England a week ago the weather has been atrocious - cold, grey and wet. And I immediately came down with a virus).
We love soups round here. They are so versatile, nutritious and tasty, so cheap and easy to make. There are limitless ways of making just a humble vegetable soup - and each time what you make always ends up a little different. Here's the recipe for yesterday's lentil and tomato soup - but I hesitate to give exact quantities as it all depends on how much spice you like, how thick you want the soup etc. (I have another recipe for this soup from The Cranks Recipe Book which results in a much thinner soup and contains no spices at all - but it's equally delicious.)
Sweat a finely chopped onion in some olive oil until soft. Add a mixture of ground spices (perhaps something like 1 tsp of ground coriander, 1 tsp of ground cumin, 1 tsp of ground turmeric, a pinch of ground cloves) and cook for 5 minutes. Then add the washed, red lentils - I think I put in around 300 gm - and a litre of vegetable stock. Cover, bring to the boil and simmer until the lentils are mushy. Empty in a couple of cans of tomatoes (you can use all sorts of combinations here - for instance fresh, ripe tomatoes and tomato juice - but if you use fresh tomatoes add these earlier) and simmer a while longer. Season to taste and it's ready! You can intensify the flavour if you want by adding things like a little yeast extract or some tomato purée. I actually cooked some chunks of potato in it as well. The whole soup has a kind of Indian dal feel about it. (I suppose you could also make a similar soup with chickpeas.) You may wish to serve it garnished with sautéed fresh chilli and coriander leaves.
Incidentally, one thing I used to do when cooking simple meals in the gîtes and albergues on the Camino was to use a cheap, packet vegetable soup as a base - and supplement it with a few fresh vegetables and perhaps some pasta, garlic, yoghurt etc. A boring packet soup can be totally transformed in this way. A good tip for flavour is to slowly caramelise an onion and fry off some finely chopped vegetables first before adding the liquid.