Gluten free sub rolls and beef liver.
Do you saute the liver in butter and add onions? 
Yes, and the onions are slightly caramelized. Liver is like shrimp and steak - it has to be cooked just right or it's ugly and dry. I've eaten it all my life so I have the timing right. The first time I had it was when I was a child; my mother, who overcooks everything, overcooked it but I fell in love with the flavor so I taught myself to make it. Never had to share.