Start with an onion, chopped.
Then saute it in the butter until it is nice and soft.
Next you add the rest of the ingredients, except the sherry and cream (and the fresh herbs if you are using them, I tend not to and just sprinkle some dried basil and parsley in whenever I remember about them). Now all you do is simmer it together. If you are making it ahead of time this is the point where you should stop and stick it in the fridge until about half an hour before you want to eat it, then you simply reheat it and carry on with the recipe.
Take you hot (or reheated) soup and turn off the heat. Pour in the sherry and cream...
....stir it all together and you are done. The recipe is here, make it the next cold, snowy day and you wont regret it.