Turns out it was a…..

Pomelo.  My mother-in-law was right.   She usually is, so this comes as no surprise.

It is like a grapefruit with a thicker skin and isn’t really at all bitter or sour, or even sweet, really. Just a delicious variation of a citrus fruit I had never tried.

All thanks to a little Russian girl in my class.  The unexpected discoveries are racking up.