I can't remember where from, possibly whole foods, but I've had some vegetable based rolls drizzled lightly in that spicy mayo stuff and it works well with certain other ingredients. It'd be disgusting to soak it in that shit though.  It's extremely offensive to the chef when you completely soak your sushi in soy sauce, so I'd imagine they don't like it when you say "can I get a bathtub of soybean oil and egg yolks to go with that?"