Introducing new foods into a picky eater’s diet can be very tricky, but going one small step at a time is important. The idea of “food chaining” gradually introduces new foods by changing components of what your child currently eats. Have you ever wondered about this: “My child will eat Dino chicken nuggets, but he just refuses to eat grilled chicken!” Think about how different a chicken nugget is from grilled chicken..taste, texture, look, smell.
If your child eats only Dino nuggets, try 
introducing different brands of nuggets. Once he is comfortable with this, you may move to lightly breaded chicken nuggets, then battered nuggets, then breaded chicken strips. Eventually, you may be able to move to regular grilled chicken*. Again, small steps are the key!
Another food chain may be to work up to a peanut butter sandwich. If your child loves those 6 packs of peanut butter crackers you could work with a sequence such as this: Ritz crackers with peanut butter, then a variety of crackers with peanut butter, then some well-toasted bread with peanut butter (maybe even cut into small circles to look like crackers), then less-toasted bread with peanut butter, then finally you may be able to move to a regular peanut butter sandwich.
I like to say that this is “an art, not a science”. You need to gradually find ONE change at a time to help introduce different foods into a diet. That may be a small texture change, different types of dips, different shapes, different brands, or different colors. The above examples are not set in stone and you could find other changes that work better for your child. You know them best, so you will be able to find those little changes that are most successful.
-Kristina SLP/FT
*Food Chaining: The Proven 6-Step Plan to Stop Picky Eating, Solve Feeding Problems, and Expand Your Child’s Diet by Cheri Fraker