"Packaged" Sushi

Question

K'vod Harav - I work in a building that has a cafeteria which sells pre-packaged vegetable sushi (of which the ingredients are simply rice, seaweed, avocado and cucumber). The package is a small plastic tray with a plastic top that is sealed with a nutritional information sticker and I have seen similar packages in supermarkets and healthfood stores. I have no idea if the sushi is made on the premises (althought I doubt that it is) or elsewhere, and, furthermore, I have no way of knowing whether the knife (or whatever) used to cut the sushi roll into the six pieces that come in the package was used for any other foods. It had seemed to me like the rice might be a problem because of bishul akum, however, I have seen a few of your responses regarding the issue of bishul akum and packaged items (including, for example, the one below) and, aside from the other possible issues, I am not sure wether I could apply your answers in those cases to the packaged sushi. Based on the explanation you provided in the response below (with respect to not having any possible connection to the non-jew who is doing the cooking) I would think that the packaged sushi is permitted, at least as far as the bishul akum issue goes. Can you tell me whether it is okay to eat the packaged vegetable sushi and why or why not? Thank you in advance for your reply and thank you for all of your hard work in conjunction with this web-site which is very informative and helpful. Tizku L'mitzvot.