I'm not an expert on this by any means but from a previous conversation with some Jewish friends, I was told that if something is prepared and/or cooked with non-Kosher equipement, it can't be used for Kosher foods. Meaning that cleaning the equipment in between would not make it Kosher if it was previously 'contaminated' with non-Kosher foods. If you cooked non-Kosher food in an oven, and then tried to cook Kosher food in the same oven, that wouldn't work. Even the way the dishes are washed can become a problem when trying to keep things Kosher (certain items have to be washed in their own dishwater). I think the main distinctions are with meat and dairy though, not veggies. Also, I'm not sure what kind of company you work for but if it involves making processed foods, there are some requirements there also (don't remember all the specifics on that, but I believe it involves the facility and food being inspected and certified). Keep in mind that just like with other religious practices, there are some variances (traditional Catholics and modern Catholics have several different practices, for example). My above statements only pertain to what I was told by this specific family and their specific practices and may not be applicable to the person who called your company. I would get in touch with that person and ask what their specific requirements are, then see if you are able to fulfill their request.