In a pot, boil enough water to cover hotdogs and boil them for five minutes.
Remove the hot dogs out of the water and keep them warm.
Cut the tomato into smallish cubes (1/2 inch or so), and season them with salt to taste
Peel and mash the avocado with a fork, discarding the pit.
Heat the hot dog rolls slightly in the oven.
For each completo, open the hot dog bun and place the hot dog inside.
Down one side of the bun, sprinkle half of the diced tomato. Down the other side of the bun, dollop and spread half of the mashed avocado. Down the middle of the bun, spread each hotdog with up to 2 tablespoons of mayonnaise, or to taste.