Here's a thought I haven't seen anyone address...
I've always been a picky eater. Although I'm better about it now, my husband still complains about my, uh, limited palate. I have a couple unscientific theories as they relate to me. Maybe this will help in some way.
I'm famous for hating cheese, onions, and coconut, and I've only started eating spicier foods in the last five to seven years (much to the hubby's relief!). Alternatively, I've always loved cereal, starchy foods, black plums, chocolate, gristly steak, milk, popcorn...
It turns out that my pickiness has served a purpose beyond being, well, picky. As much as I love milk, it turns out that I'm somewhat intolerant of it, which explains some GI issues. I still love to drink milk, but other dairy products don't usually appeal to me. Okay, ice cream is good. ;-) But cheese, yogurt, creamy sauces... I've always eschewed these things for other choices. So dairy, onions, and too many spices cause me digestive discomfort. It also turns out that I'm very mildly allergic to coconut and coffee. I also hate tofu: I'm mildly allergic to soy. (Don't ask me why I love corn--I'm mildly allergic to that, as well.) I'm NOT allergic to wheat (thank goodness), and I find that I crave pasta, cereals, bread, and such.
Unfortunately, I have bad junk food habits, too. I'm getting better because I have a five-year-old and almost five-month-old.
My mom tried to lay down the law, but if I wanted something, I'd get it, whether from school or the convenience store, I'd find it.
I guess the point I'm trying to make--and please excuse if htis is rambling because I'm very tired due to the little guy having a worsening cold on top of teething--is that your daughter's pickiness may serve a function. Get her check for food allergies, and see if she has a sensitive stomach.
Finally, I've found that I really like Spanish (European) food, especially Tapas-style foods, and some Indian food (curries are good). Sushi with cooked meat is really good, as well. It's expensive pre-made, but mayube you can improvise at home. It can be fun and colorful.
Hope this helps.