Food is often the first thing that the little darlings realise they can exert real power over! We are programmed to want to nuture them, and when they refuse to eat, it presses all our buttons.
Many years ago I was given a copy of "Toddler Taming" by an Australian chap whose name I can't remember, but it did have some good quite laid back advice re eating.
The advice about letting them build pizzas etc is good. Some children will also respond better to veg presented as finger food. When are 2 were small, we did insist that new foods were at least tried and not just dismissed out of hand.
Last weekend, in Rutland, the first statue in Britain of the late Elizabeth II was unveiled.