Can I Buy a Non-Jew a Sandwich on Passover?

I was trying to help someone on the street get some food. They asked for a sandwich, so I went into a nearby shop—and suddenly panicked because I realized it was Passover! What was I supposed to do in this case? What are the parameters of buying and touching hameitz for non-Jews during the holiday?Have a question you'd like answered on Responsa Radio? Email us at [email protected]