It's easy to get frustrated with a child who simply won't eat anything new. But it's important to avoid setting up a situation in which you and your child are vying for power. The best way to avoid a power struggle is to set the bar low enough that your child will almost always succeed.
That may mean micro-mini steps at first - sniffing a food, tasting with the tongue, and so forth - and the journey may take a while. But as your child succeeds, step by step, and wins your pride and motivating rewards, you may find it a more pleasant way to set your goals.