This soup, made with the bacon stock from Boiled Smoked Bacon, is so named because of the thick, dense 'peasouper' London fogs that were so prevalent during the first half of the last century.
You can use any beans in this recipe, but borlotti are the best of all. The smokiness of the pancetta is also important, but if you can't get it, use smoked bacon.
This is my version of an old Italian favourite, and I think the addition of a sharp lemon dressing and some buttery rocket leaves gives a lovely edge. If you forget to soak the beans overnight, you can...