In the middle: egg salad, sliced tomato, ham salad. “Frosted” with whipped cream cheese. From Better Homes and Gardens cook book ca. 1968.
Serving slice with time-appropriate drinks:

In the middle: egg salad, sliced tomato, ham salad. “Frosted” with whipped cream cheese. From Better Homes and Gardens cook book ca. 1968.
Serving slice with time-appropriate drinks:

I never have figured out what to do with it, but when I was a kid I mixed mayo with tomato paste and it is tasty. It should go on some sort of sandwich.
I also grew up eating ketchup on my scrambled eggs. And I’d make a scrambled egg sandwich with mayo on the bread. All tasty.
So really, for me, egg an mayo and tomato have several possible ways to make it work :)