Completo Italiano.

The hot dog reached Chile in the first half of the twentieth century, arriving with the same wave of American food and diner formats that spread through South American cities, and it was immediately taken apart and rebuilt. Chilean cooks were already producing enormous quantities of avocado and already treated mayonnaise as something closer to a vegetable than a condiment, so both went on the bun. Exactly who did it first is contested, with Santiago sandwich counters and their descendants each claiming the origin, and there is no settled answer worth repeating as fact. What is clear is that the result stopped being an imported novelty a long time ago: the completo now sits alongside the empanada and the churrasco in the country's sandwich canon, and Chileans consume them at a rate that startles visitors.

The naming system is worth learning, because ordering wrongly gets you a different sandwich. Italiano is the three-colour version described here. A completo dinámico adds sauerkraut, ketchup and mustard to the pile. A completo alemán swaps the avocado for sauerkraut and onion. Simply asking for a completo generally gets you sauerkraut, tomato and mayonnaise, and the phrase completo con todo means what it sounds like. The same logic runs through Chilean sandwiches generally — a churrasco italiano, an as italiano and a chacarero all follow their own fixed rules — which is why a Chilean menu can look like a list of proper nouns.

The avocado deserves specific attention, because it is not a garnish here. Chileans call it palta, grow a great deal of it, and mash it plain: no lime beyond a little for colour, no garlic, no chilli, no coriander. Guacamole this is not, and treating it as such changes the sandwich into something else entirely. The mayonnaise, meanwhile, is applied in a layer thick enough to be structural, and cutting it back to a polite smear is the surest way to make a completo that tastes like a plain hot dog with vegetables on it.