A Martinmas meal is typically very simple and sometimes includes a food that can be cut in half and shared with your family member next to you, imitating the gesture of Martin cutting his cloak in half and giving it away.
Martin of Tours didn't want to become bishop. So he hid in a goose pen. But the geese made a racket, so they found him and made him bishop anyway. Martin killed one of the geese that outed him, so the tradition was to eat a goose on St. Martin's day, which is coming up in a few days.