One of my "aquired" grand daughters is a picky eater. Her parents use to make her whatever she'd eat. One of the main dislikes is bread. She loves cornbread miffins, but hates sandwich or anything labeled bread.
Now I know I'm going to get a LOT of flack here, but I've raised several kids including my own, and this does work. Its harder on you than your picky eatter.
We have two choices at my house:
1) eat what I make
2) do without
That means NO snacks etc. We have what we call the "thank you" bite. That is a bite of everything fixed for that meal. I always fixed something the picky person liked (I did say its harder on you) and then I made what was planned for dinner. Picky had to eat one bite (not big, but enough to taste) what was fixed and then could eat the thing they liked, but no desert and not snacks later either. Also, they helped their own plates.
I remember well my father helping my plate and ther was no way I could eat all of it and if it was liver night ughhhhhhhhh! So, I let them help their own plates so they choose how big a bite they will eat.
Some times kids or adults feel they have no comtrol over anything and they use food. They can control that by not eating, or over eating. By giving them control over themselves and the food it usually will work itself out. It has for all the picky eaters I'd had to endure
By the way, the one I have now will eat 1 bite of bread from her McDonald's Hambugar bun, and she is trying new foods here and when we go out. It may only be one new item, but she is trying!
Her is a site you might find some potato recipes
http://www.idahopotato.com/
Good Luck!