Vromiko (dirty food) has been an Athenian staple for people leaving clubs and ending their nights. It traditionally consists of a hot dog bun containing sausage, potato fries, shredded carrots and cabbages, and ketchup or mustard or mayo. Vromiko is served in canteens along the streets where clubs or football stadiums are situated. It is intended as comfort food when you had too much to drink (and/or dance and sing). Athenians take their nightlife very seriously, so it is the norm to leave the club after 05:00 and search for rich, hot food before going to bed (check the Ciao Italia article).
Lately, many places have started experimenting with vromiko, e.g. adding caramelized onions or vegan sausages but nothing crazy so far. Vasilis canteen is, of course, located in the busy street near many popular clubs. It is a family-run business, being in the same place for more than 20 years. Vasilis himself is not working anymore but his kids have taken over and have many stories to tell, such as their primary school years when vromiko was their usual school lunch. I love the Vasilis canteen because it is the real thing; huge sausage sandwiches where mayo is applied with a small trowel. There are no great divergences in the menu. You can either get boiled or grilled sausage, chicken nuggets, or meat patties. The filling is limited to carrots/cabbage, cheese, fries, and sauces. Stay up late and eat Vasilis vromiko before your morning coffee for an unforgettable Athenian experience.