Probably the best cookery book I ever used (apart from Larousse Gastronomique, which is not, strictly speaking a cookery book, and Elizabeth David) was Anne Willan's Observer French Cookery School. Of course, it being rather good, it is out of print. I first collected it, in parts, free with the Observer. The paper then went on strike and I never finished collecting them, though I did have a copy that went, like everything else, to my first wife.
Anyway, the strength of the book was in its explanations. It really did teach you how to make a good stock or what a proper saute was. So, with that in mind, here is Weasel's winter warmer soup, with explanations for those who are new to the basics.
The basis of a soup is the stock. You can use beef, chicken or vegetable. The only bought stock cubes I use are the Kallo organic ones. The rest tend to include too much salt. I am not ashamed to use bought stock if it is good. Making stock though, is fun. My method with beef stock is always the same: After eating boiled beef and carrots, using Brisket, I reduce the liquid considerably from say, two litres to a pint, or even half a pint, adding bouquet garni, which in my case is a combination of bought and fresh herbs, including bay. In the case of this method, the carrot and onion have already added to the flavour. Supermarkets now sell ready made liquid stock, and this is fine if you don't make your own. Check though for salt content.
The obvious candidate for beef stock (which is always described in the recipe books as taking longer than a manned flight to Mars) is Onion Soup. And you don't need to reduce the liquid. The onions are fried, in olive oil and butter (not too much) until they are caramelised. Some people add a spoonful of sugar. Certainly (and carefully) add some salt and pepper. This is a soup that requires thickening in some way. Before you add the hot stock to the onions, you can add a little plain flour, say one level dessert spoon per litre, until it is soaked into the onions. Then you can add the hot stock. This all benefits from the addition of a little sherry. Traditionally, Onion soup is served with crusty baguette that has melted cheese on the top.
The lentils will, if cooked slowly, provide enough bulk, and do not need anything to thicken them. For flavour, I make up a classic mirepoix, which is a mix of chopped onions, carrots and celery, slowly sweated in butter.
After the lentils have started to disintegrate, add the mirepoix. I also add a teaspoonful or two of Marigold vegetable stock and a teaspoon of Garam Masala. This last thing is vital to my version, since it transforms a very ordinary soup into something that actually tastes interesting.
If you like animal flesh, you can add bits of shredded cooked hough or bacon, but it is not essential.
Here endeth the lesson. Any soup recipes you have are very welcome indeed.