The key to ajiaco is the three potatoes. Colombian cooks use a floury potato called 'papa criolla' (which dissolves into the broth and makes it thick and creamy), a waxy potato called 'papa pastusa' (which stays in chunks), and a third variety that adds flavour. The combination gives the soup its rich, velvety texture.
Guascas is a dried herb that grows in the Andes - it has an earthy, slightly tangy flavour that you cannot really substitute with anything else. It is the ingredient that makes ajiaco taste like itself and nothing else. Colombians who live abroad often bring dried guascas in their suitcases because no other herb does the same job.
Ajiaco is traditionally served with a little pot of cream and capers on the side, which you stir into the hot soup yourself. Some families add avocado slices to the top. The corn is kept on the cob in the soup - you pick it up and eat it by hand, which makes ajiaco a hands-on, happy kind of meal.
Bogotá sits at 2,600 metres above sea level - high up in the Andes, where the air is thin and the evenings can be quite cool. Ajiaco is perfectly designed for this climate: thick, warming and filling. It is the official comfort food of the Colombian capital.