Subway

Question

Dear Rabbi Abadi: I am also reasonably new to this site and apologize if these questions have been asked and answered previously. Are we not concerned about the kelim used to make the Tuna salad/sandwich. For example, what would the halacha be if the attendant used a knife or spreader that was just used on a piece of meat (I picture the fat of the meat still on the knife) to make the sandwich. Also, is it not dangerous to eat in such places, as it might bring someone to eat actual non-kosher food, as these places become more frequented as a matter of course. Lastly, are Subway locations in Canada included in your psak. Thank you for your patience.