The Division of Responsibility developed by dietitian Ellyn Satter is well-supported by research: the parent decides what, when, and where food is offered; the child decides whether to eat and how much. Removing power struggles from mealtimes reduces anxiety around food.
Repeated exposure without pressure is effective. A new food may need to be presented 15 to 20 times before a child accepts it. Involving children in simple food preparation and eating the same food yourself normalises new tastes gradually.