Dice the tomatoes. You’ll want to have about 1 cup of finely chopped tomatoes.

Mash the avocados with a fork or a potato masher. Optionally, add a tablespoon of mayo to the mashed avocado (it seasons it and prevents it from going brown). If you plan to use less (or no) mayo for the topping, add a good pinch of salt and black pepper to season the avocado more.

Cook the hot dogs. Fill a pot with water and bring it to a boil. Add the hot dogs and simmer them for about 4 minutes (or more if frozen).

(Optional) Steam the hot dog buns on top of the pot of boiling water by placing a rack on top of the pot and the buns on top of the rack (for about 1 minute, turning the buns after 30 seconds).

Assemble the hot dog, slicing the bun first, then adding the Vienna sausage/Frankfurter, chopped tomatoes, then mashed avocado, and finally, the mayonnaise to taste.