Hi L.,
This is one of the most common complaints on the sight and with my friends who have kids. I have 2 step sons that are in their mid twenties now and went through this when they were younger and now have a son of my own who is 9. They all had their phases of being picky eaters, my oldest was continually allowed to control everyone around him by having separate meals made, throwing fits when he didn't get what he wanted...he is still that way today, he is 27.
With my next step son and my youngest I did what some call tough love but I learned about it in a course about child rearing, don't give in on this particular item. Fix a meal and that is it. If they don't like it they don't have to eat it but they don't get to fix something else. They will eventually eat when they are hungry enough. My petiatrician says they won't starve themselves.
You can also make cooking fun where they participate, my 9 year old has been cracking eggs, stirring, helping pick fruit and veggies out at the market... since he was 18 months, not always the cleanest thing to do but they have fun doing it, want to try the foods they helped make, they learn about measuring, weight, responsibility, participation....
Also keep in mind it takes a lot of times for something to taste good to a kid, they may have to try it 15 different times, before their taste buds say it is good so have at least one item you know they have liked before. If they don't like it now then don't eat it but nothing else will be made. It didn't take long for my younger step son and my son to be fine with whatever we had.
It is only the last couple generations that have had the luxury of saying 'I don't like this I want something else'. My son loves the stories of how in pioneer days they ate whatever was shot that day with very simple biscuits and were happy to have it. He said he feels lucky we have so many choices.
Make it fun and don't be manipulated because it teaches really bad habits that last a life time.
S. M