Something that will help keep it soft
My parents were in the restaurant business and the liver was always steamed a bit with either a little Sherry or more often with some Chicken Broth after the liver was browned, but not cooked through...and that is how I cook it to this day and since I am 76 that is a lot of days. Also, if she is going to use High try to prevail upon her to heat it for a very short time. I would start with about 30 seconds and then if more heat is needed increase by 10 seconds at a time.
Hope this helps and now I have a craving for some Chicken Livers
Sandy in Baltimore