I don't think this appeals to me any more than it does to you guys, but it does remind me of a few things from Japan (where I did a postdoc).
When I was obliged to go to a fast food burger place by nostalgic fellow westerners, I would skip the burgers and instead get a very lightly cooked vegetable thing between two grilled sticky rice things. I think this is it: http://www.mos.co.jp/menu/rice/kinpira/
. My original aim was to avoid the most blatantly treif items, but even now I think this item was actually pretty decent, and not only because of the contrast with the rest of the menu, which was even less appealing to me than McDonalds et al. The rice things that substitute for hamburger buns are clearly adapted from a common Japanese food, yaki onigiri, grilled rice triangles. The Japanese put mayonnaise on a dismayingly (from the perspective of someone who doesn't like mayonnaise) large number of foods, such as, for example, pizza (along with katsuobushi, dried bonito shavings), so I can see where the inventor of the sushi hamburger got the idea for mayonnaise.