Leftover meatloaf, cold, on fresh white bread. Any kind of mustard, but spicy brown is nice.
Now, leftover turkey offers many possibilities...leftover turkey sandwiches are the best part of Thanksgiving dinner - especially if you’re the one who slaved over the meal :-)
When my Mother packed our lunches for school back in the 50’s it was always Piccalilli on meatloaf sandwiches and cranberry sauce on chicken sandwiches, but Kraft mayonnaise on everything else even bologna sandwiches. She did put mustard on Deviled Ham sandwiches.