We are going to open a kosher restaurant soon and my fiance (who hasnt converted yet) will be a part of it. According to the Halacha, what is he allowed to do in the restaurant that wont jeopardize the kosher certification of the food? I know hes not allowed to turn the fire on, or touch wine etc. but is he allowed to put stuff (like salad pickles etc.) in a pita for instance without it voiding kosher? What can he do there?