This is on the lunch menu at 2it & Drink, but I don't think it's on the main menu. Apparently this is a tradtional configuration of tuna and onions though, and it worked for me, especially since the tuna didn't remind me of childhood sandwiches.
The atmosphere was really casual. Reminded me of iO Italian Osteria because of both their naming styles and the setup.
Overall, 2it & drink is definitely a place I would recommend you try at least once.