Interestingly, research on “supertasters” (which most picky eaters are) indicates that it can take ten or more times tasting something before it’s considered edible. I didn’t require a full bite from either child for any food, but I did tell them about the research and did ask that they attempt to taste anything that made them suspicious. (I did pay my son a dollar to try chocolate when he was five. That was fun.) Meals often included two or three options that were reasonable, and the kids were always welcome to fill up on bread and butter and an apple. (I made the bread and it had whole wheat, with eggs and milk in it, so it wasn’t empty calories.)
Because I grew up with food issues around my mother’s severe food restrictions (she ate nothing but steak and salad for many years and wouldn’t allow cookies or sugars in the house), I was very careful about creating food issues in my kids. They were never forced to eat nor restricting from eating when they were hungry, even if it was “just before dinner”. In the “just before dinner” window, I always started by cutting up carrots and apples and would continue to a slice of bread and butter if necessary. (I still start dinner by slicing up carrots, only now I nibble on them while I’m cooking, instead of feeding them to the kids.) I knew I was succeeding when my daughter handed me half a cookie and asked me to save it for later because she wasn’t that hungry–she was five. She asked for the second half two days later.
Both my kids (now 29 and 30) are far more adventurous about food than I am at this point. My daughter keeps telling me I should “just try that, you might like it.”