You can put almost anything on and in it, or nothing at all, like a burger. The $15 one above is $15 because it has shrimp. You could make beluga 000 caviar avocado toast with foie gras and gold flakes and charge $500 for it and someone will buy it, or it will at least make a YouTube hit. In the end the base idea is just avocado spread on toast. As usual the culinary and carnival worlds take ordinary foods to fun, weird and extreme (and ridiculous) places.
This is in response to recent suggestions that avocados, almonds, and other crops are not vegan due to reliance on mobile bee hives to pollinate. Obviously these things are vegan, but the commercial farming of these crops due require bees to be brought in, which reportedly reduces the lifespan of the bees. Just depends on how far you want to take your avoidance of animal agriculture.